H3C UniServer R4950 G6 User manual

H3C UniServer R4950 G6
Technology White Paper
Copyright © 2023 New H3C Technologies Co., Ltd. All rights reserved.
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New H3C Technologies Co., Ltd.
Except for the trademarks of New H3C Technologies Co., Ltd., any trademarks that may be mentioned in this document
are the property of their respective owners.
The information in this document is subject to change without notice.

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Contents
Overview························································································1
Product features ··························································································································2
Higher performance and security features··················································································2
More flexible storage and higher I/O performance········································································2
Intuitive and configurable management system···········································································3
Exceptional server experience·································································································3
Low-carbon and environmentally-friendly···················································································3
Customized services··············································································································4
Server topology ···························································································································4
Server specifications·········································································5
Components ·······························································································································5
Front panel ·································································································································7
Front panel view of the server··································································································7
LEDs and buttons··················································································································9
Ports·································································································································10
Rear panel································································································································ 11
Rear panel view··················································································································11
LEDs ································································································································ 13
Ports·································································································································13
NOTE: ·························································································14
System board···························································································································· 14
System board components···································································································· 14
System maintenance switch ··································································································16
DIMM slots·························································································································17
HDDs and SSDs························································································································ 18
Drive numbering·················································································································· 18
Drive LEDs························································································································· 19
Drive backplanes ·······················································································································20
Front 8SFF SAS/SATA drive backplane··················································································· 20
Front 8SFF UniBay drive backplane························································································21
Front 8LFF SAS/SATA drive backplane··················································································· 22
Front 12LFF SAS/SATA drive backplane ················································································· 22
Front 12LFF 8SAS/SATA+4UniBay drive backplane ··································································22
Front 12LFF4SAS/SATA+8UniBay drive backplane···································································23
Front 12LFF UniBay drive backplane ······················································································24
Front 25SFF 17SAS/SATA+8UniBay drive backplane ································································25
Mid 4LFF SAS/SATA drive backplane ····················································································· 25
Rear 2LFF SAS/SATA drive backplane ···················································································26
Rear 4LFF SAS/SATA drive backplane ···················································································26
Rear 2SFF SAS/SATA drive backplane··················································································· 27
Rear 2SFF UniBay drive backplane ························································································27
Rear 4SFF SAS/SATA drive backplane··················································································· 28
Rear 4SFF UniBay drive backplane ························································································28
Riser cards ·······························································································································29
RC-3FHFL-2U-G6 ··············································································································· 29
RC-3FHHL-2U-G6···············································································································31
RC-2FHFL-2U-LC-G6 ·········································································································· 33
PCA-R4900-4GPU-G6 ········································································································· 34
Riser 4 assembly module (accommodating two FHFL PCIe modules) ··········································· 35
Riser 4 assembly module (accommodating two HHHL PCIe modules)···········································36
Riser 3 assembly module (accommodating two HHHL PCIe modules)···········································37
Fan modules·····························································································································37
Liquid cooling system (for liquid-cooled model)················································································ 38
B/D/F information······················································································································· 38

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Installation guidelines······································································39
Processors ······························································································································· 39
DIMMs····································································································································· 39
SAS/SATA drives·······················································································································39
NVMe drives ·····························································································································39
M.2 SSDs·································································································································40
Server management module ········································································································41
Serial & DSD module··················································································································42
Riser cards and PCIe modules ·····································································································43
Riser card and PCIe module compatibility················································································43
Riser card and PCIe module compatibility················································································44
Storage controllers and power fail safeguard modules·······································································48
Storage controllers ··············································································································48
Powerfail safeguard modules·································································································48
Installation guidelines··········································································································· 48
Network adapters················································································································49
GPU modules····························································································································49
Power supplies··························································································································50
Fan modules·····························································································································51
Product specifications ·····································································52
Technical specifications ··············································································································52
Operating environment requirements ····························································································· 53
Component compatibility··································································54
Processor·································································································································54
DIMMs····································································································································· 54
About DIMMs ·····················································································································54
DRAM DIMM rank classification label······················································································ 54
Guidelines·························································································································· 55
Storage···································································································································· 56
I/O expansion····························································································································57
Intelligent management ···································································58
Maintenance ·················································································60
Certifications·················································································61

1
Overview
H3C UniServer R4950 G6 is a 2U dual-processor enterprise-level high-performance rack server
developed by H3C. It is supports AMD EPYC Genoa, Genoa-X, and Bergamo processors. The
server offers strong computing power, high reliability, flexible scalability, and easy management and
deployment, making it suitable for virtualization, cloud computing, high-performance computing, and
AI applications.
The server can provide the following benefits:
•Efficient and versatile computing power
Supports up to two AMD EPYC 9004 processors.
Supports up to 256 physical cores.
Supports up to four dual-width GPU modules.
Supports various computing units such as xPU.
•High-speed I/O transmission
Supports up to 24 new DDR5 DIMM slots.
Supports the memory rate of up to 4800MT/s.
Supports CXL 1.1 interconnect protocol.
Supports up to 28 U.2 NVMe SSDs.
Supports up to 36 E3.S drives (1TB) (not yet released).
Supports up to 18 E3.S drives (2TB) (not yet released).
Supports up to 40 E1.S drives.
Air-cooled models support up to 10 standard PCIe 5.0 slots.
Liquid-cooled models support up to 9 standard PCIe 5.0 slots.
•Multilayer security protection
Supports chassis intrusion detection.
Supports Secure Memory Encryption (SME).
Supports Secure Encrypted Virtualization (SEV).
Supports Trusted Platform Module (TPM).

2
Product features
Higher performance and security features
•Supports the AMD EPYC 9004 series processors, with a maximum of 128 cores, a maximum
frequency of 4.1GHz, and 384MB cache per processor.
•With support for dual processors, a single server can support up to 256 cores and 512
threads, maximizing the server's multi-threading capabilities and parallel processing
performance.
•Supports up to 24 4800MT/s DDR5 ECC memory modules, providing larger memory
bandwidth and capacity for the system.
•The liquid-cooled model's heatsink module supports two options, outlet hose connectors +
quick connectors and quick connectors fixed to the back, supporting water-electric
separation.
•Includes a RAID controller that uses a standard PCIe connector, providing high-speed cache
for data read/write operations and supporting power failure protection.
•Supports an M.2 RAID controller in standard form, supporting RAID0 and RAID1.
•Comes with an efficient universal slot power supply, supporting 100V-288V AC, 288V HDC,
80+ Platinum or higher power supplies, and a maximum of 2400W power supply to enable up
to 94% energy efficiency.
•Supports PCI Express 5.0 and SAS4.0 (not yet released), which helps to reduce I/O latency
and improve overall system performance.
•Supports CXL1.1, which can provide a high-performance, low-latency solution (not yet
released),and VXLAN features, which can help reduce network load, simplify configuration
and deployment, and enhance the security and multi-tenancy capabilities of cloud computing
applications.
•Supports SR-IOV features through virtualization technology, which can provide users with
exclusive network resources, simplify management, ensure business security, and enhance
user experience.
•Supports a TCM/TPM trusted platform module, which offers advanced security encryption
functionality.
•Supports enhanced chip security encryption technology, enabling memory encryption and VM
encryption for enhanced data security and reliability during transmission.
More flexible storage and higher I/O performance
•Support multiple flexible hard disk configuration options, providing users with elastic and
scalable storage capacity space, meeting various storage capacity needs and upgrade
requirements.
•Supports SSD configuration, which significantly improves I/O performance compared to
mixing SSDs with HDDs or using only HDDs.
•Supports PCIe NVMe SSD configuration to maximize I/O performance.
•Supports E1.S and E3.S configurations to significantly improve capacity and scalability (not
yet released).
•The air-cooled and liquid-cooled models support up to 10 and 9 standard PCIe 5.0 slots,
respectively, significantly enhancing system expansion capabilities.
•The air-cooled and liquid-cooled models support up to 4 and 3 dual-width or 9 single-width
GPU modules, respectively, enabling comprehensive workload acceleration and empowering
machine learning and artificial intelligence applications.

3
•Uses the intelligent RAID controller that support high-speed caching, significantly improving
I/O performance.
Intuitive and configurable management system
•The HDM system management module can be used to monitor system status and provide
remote management functions.
•The UniSystem management software allows for diskless installation and deployment of
servers, with device drivers that can be upgraded online.
•Virtual media, remote consoles, and virtual KVM functionality can all be implemented through
the HDM management system.
•Supports two OCP3.0 network adapters and two dedicated OCP3.0 SFF NIC slots (not yet
released), supporting sideband management (NCSI) features, and allowing for management
network port and business network port reuse. NCSI features can be flexibly configured
through HDM.
•Supports standardized UEFI interfaces, improving the efficiency of system settings,
configuration, and updates, and simplifying error handling processes.
Exceptional server experience
•Features precise fan control for direct cooling and innovative temperature sensors with a 3D
temperature array that reduces unnecessary fan power, resulting in lower system noise and
power consumption.
•Uses dynamic workload acceleration to provide intelligent data protection capabilities for
expanding hard drive capacity, while supporting real-time workload analysis to adjust and
optimize storage performance.
Low-carbon and environmentally-friendly
•The liquid-cooled model significantly improves heat dissipation capabilities through the cold
plate-based liquid-cooled module, allowing for a maximum processor temperature reduction
of 30°C (86°F). This results in a 6%-30% reduction in overall system power consumption and
keeps the overall system noise below 60dB, improving the operating environment in data
centers.
•Offers 80 PLUS Platinum power supply modules with different power levels, achieving up to
94% efficiency at 20% load.
•Supports primary and backup power supplies with human-controlled entry into cold backup
mode, which improves power efficiency.
•Supports working temperatures ranging from 5°C to 45°C (41°F to 113°F), further reducing
energy consumption. (The working temperature is affected by different configurations. See the
detailed product technical documentation for more information).
•Features partitioned fan speed control and Proportional-Integral-Derivative (PID) intelligent
speed control for the system cooling fan and intelligent frequency adjustment for the
processor, saving energy and reducing consumption.
•Adopts a comprehensive system cooling design to optimize energy efficiency of the system
cooling fan. The system also supports processor liquid cooling to reduce system cooling
energy consumption.

4
Customized services
H3C independently researches, designs and owns intellectual property rights for its products. Our
strong production and supply capabilities ensure rapid delivery of customized solutions.
Server topology
•R4950 G6 supports two AMD EPYC 9004 processors and up to 24 DDR5 DIMMs. The
processors are interconnected by four XGMI buses, each with 16 lanes. The overall PCIe
resources adopt a NUMA balance design.
•The onboard SATA connector for processor 1 supports two M.2 slots and eight SATA ports
(compatible with SATA/NVMe) or 16 SATA ports (compatible with SATA/NVMe). Processor 2
supports 16 SATA ports (compatible with SATA/NVMe).
•The onboard NVMe connector for processor 1 supports up to 12 NVMe SSDs (6 MCIO x8),
while processor 2 supports up to 16 NVMe SSDs (6 MCIO x8 + GENZ-4C).
•The processors are connected to four PCIe riser cards via PCIe buses, and different PCIe slot
specifications are supported through different riser cards.
•The system board provides two OCP 3.0 network adapter slots, which can be flexibly
configured with PCIe 5.0 *8 and PCIe 5.0 *16 links, and support hot swappable.
•The AST2600 management chip is used, which supports VGA, management network port,
debugging serial port, and other management interfaces.

5
Server specifications
Components
Figure 1 Server components
Item
Description
(1) Chassis access
panel
N/A
(2) Processor
heatsink
Cools the processor.
(3) OCP network
adapter
Network adapter installed onto the OCP network adapter connector on the system
board.
(4) Processor
Integrates memory and PCIe controllers to provide data processing capabilities for
the server.
(5) Storage controller
Provides RAID capability to SAS/SATA drives, including RAID configuration and
RAID scale-up. It supports online upgrade of the controller firmware and remote
configuration.
(6) Standard PCIe
network adapter
Installed in a standard PCIe slot to provide network ports.
(7) Riser card
Provides PCIe slots.
(8) Memory
Stores computing data and data exchanged with external storage temporarily.
The server supports DDR5 DIMMs.
(9) Processor socket
cover
Installed over an empty processor socket to protect pins in the socket.
(10) Server
management module
Provides I/O connectors and HDM out-of-band management features.
(11) System board
One of the most important parts of a server, on which multiple components are

6
installed, such as processor, memory, and fan. It is integrated with basic server
components, including the BIOS chip and PCIe connectors.
(12) Rear drive
backplane
Provides power and data channels for drives at the server rear.
(13) Rear drive cage
Installed at the server rear to accommodate drives.
(14) Riser card blank
Installed on an empty PCIe riser connector to ensure good ventilation.
(15) Power supply
Supplies power to the server. The power supplies support hot swapping and 1+1
redundancy.
(16) Chassis
N/A
(17) Chassis ears
Attach the server to the rack. The right ear is integrated with the front I/O component,
and the left ear is integrated with VGA connector, dedicated management connector
(Type-C), and USB 3.0 connector.
(18) Front drive
backplane
Provides power and data channels for drives at the server front.
(19) Drive
Provides data storage space. Drives support hot swapping. Both SSDs and HDDs
are supported and the supported drive interface types include SAS, SATA, M.2, and
PCIe.
(20) Supercapacitor
holder
Secures a supercapacitor in the chassis.
(21) Supercapacitor
Supplies power to the flash card on the power fail safeguard module, which enables
the storage controller to back up data to the flash card for protection when power
outage occurs.
(22) SATA M.2 SSD
expander module
Provides M.2 SSD slots for installing SATA M.2 SSDs.
(23) SATA M.2 SSD
Provides data storage space for the server.
(24) Serial & DSD
module
Provides one serial port and two SD card slots.
(25) SATA M.2 RAID
controller
M.2 SSDs installed at the rear. The SSDs support RAID configuration and can be
used for operating system installation.
(26) Encryption
module
Provides encryption services for the server to enhance data security.
(27) Fan cage
Accommodates fan modules.
(28) Fan
Helps server ventilation. Fans support hot swapping and N+1 redundancy.
(29) System battery
Supplies power to the system clock to ensure system time correctness.
(30) Chassis open-
alarm module
Detects if the access panel is removed. The detection result can be displayed from
the HDM Web interface.
(31) Air baffle
Provides ventilation aisles for processor heatsinks and memory modules and
provides support for the supercapacitor.
(32) Processor liquid-
cooled module
Cools processors.

7
Front panel
Front panel view of the server
Figure 2 8LFF front panel
Table 1 8LFF front panel description
Item
Description
1
USB 3.0 connector
2
Drive or LCD mart management module (optional)
3
Serial label pull tab
4
Dedicated management connector
5
USB 3.0 connector
6
VGA connector
Figure 3 12LFF front panel
Table 2 12LFF front panel description
Item
Description
1
12LFF UniBay drives (optional)
2
USB 3.0 connector
3
Drive or LCD mart management module (optional)
4
Serial label pull tab
5
Dedicated management connector
6
USB 3.0 connector

8
Item
Description
7
VGA connector
*: Drive types supported by the server vary by drive backplane configuration. For more information, see
"Drive backplanes."
Figure 4 8SFF front panel
Table 3 8SFF front panel description
Item
Description
1
Bay 1: 8SFF drives (optional)*
2
Bay 2: 8SFF drives (optional)*
3
Bay 3: 8SFF drives (optional)*
4
USB 3.0 connector
5
LCD smart management module (optional)
6
Serial label pull tab
7
Dedicated management connector
8
USB 3.0 connector
9
VGA connector
*: Drive types supported by the server vary by drive backplane configuration. For more information, see
"Drive backplanes."
Figure 5 25SFF front panel

9
Table 4 25SFF front panel description
Item
Description
1
25SFF drives*
2
USB 3.0 connector
3
Drive or LCD mart management module (optional)
4
Serial label pull tab
5
Dedicated management connector
6
USB 3.0 connector
7
VGA connector
*: Drive types supported by the server vary by drive backplane configuration. For more information, see
"Drive backplanes."
LEDs and buttons
Front panel LEDs and buttons
Figure 6 Front panel LEDs and buttons
Table 5 LEDs and buttons on the front panel
Button/LED
Status
Power on/standby button
and system power LED
•Steady green—The system has started.
•Flashing green (1 Hz)—The system is starting.
•Steady amber—The system is in standby state.
•Off—No power is present. Possible reasons:
No power source is connected.
No power supplies are present.
The installed power supplies are faulty.
The system power cords are not connected correctly.
OCP 3.0 network adapter
Ethernet port LED
•Steady green—A link is present on a port of an OCP 3.0 network
adapter.
•Flashing green—A port on an OCP 3.0 network adapter is receiving or
sending data.
•Off—No link is present on any port of either OCP 3.0 network adapter.
NOTE:
The server supports a maximum of three OCP3.0 network adapters.

10
Button/LED
Status
Health LED
•Steady green—The system is operating correctly or a minor alarm is
present.
•Flashing green (4 Hz)—HDM is initializing.
•Flashing amber (1 Hz)—A major alarm is present.
•Flashing red (1 Hz)—A critical alarm is present.
If a system alarm is present, log in to HDM to obtain more information about
the system running status.
UID button LED
•Steady blue—UID LED is activated. The UID LED can be activated by
using the following methods:
Press the UID button LED.
Activate the UID LED from HDM.
•Flashing blue:
1 Hz—The firmware is being upgraded or the system is being
managed from HDM. Do not power off the server.
4 Hz—HDM is restarting. To restart HDM, press the UID button LED
for eight seconds.
•Off—UID LED is not activated.
Ports
Table 6 Ports on the front panel
Port
Type
Description
VGA connector
DB-15
Connects a display terminal, such as a monitor or KVM device.
USB connector
USB 3.0
Connects the following devices:
•USB flash drive.
•USB keyboard or mouse.
•USB optical drive for operating system installation.
Dedicated
management
connector
Type-C
Connects a Type-C to USB adapter cable, which connects to a
USB Wi-Fi adapter.
NOTE:
The server supports only Xiaomi USB Wi-Fi adapters.

11
Rear panel
Rear panel view
Figure 7 Rear panel components
Table 7 Rear panel description
Item
Description
1
PCIe slots 1 through 3
2
PCIe slots 4 through 6
3
PCIe slots 7 and 8
4
PCIe slots 9 and 10
5
Power supply 2
6
Power supply 1
7
OCP 3.0 network adapter/Serial & DSD module (optional)
8
VGA connector
9
Two USB 3.0 connectors
10
HDM dedicated network port (1Gbps, RJ-45, default IP address 192.168.1.2/24)
11
OCP 3.0 network adapter (optional)
For more information about the serial & DSD module, see "Serial & DSD module."
When the server is installed with the liquid-cooled module, slot 6 on the rear panel will be used to
install the inlet and outlet ports. The quick connectors will be differentiated into male connectors and
hose connectors, as shown in Figure 8 and Figure 9, respectively.

12
Figure 8 Rear panel components (Processor liquid-cooled module with male connector)
Figure 9 Rear panel components (Processor liquid-cooled module with hose connector)
Figure 10 Description of rear panel components (CPU liquid-cooled module)
Item
Description
1
PCIe riser connector 1: PCIe slot 1 to slot 3
2
PCIe riser connector 2: PCIe slot 4 and slot 5
3
PCIe riser connector 3: PCIe slot 7 and slot 8
4
PCIe riser connector 4: PCIe slot 9 and slot 10
5
Power supply 2
6
Power supply 1
7
OCP 3.0 network adapter or serial & DSD module (slot 17) (optional)
8
Outlet of the liquid-cooled module (red)
9
Inlet of the liquid-cooled module (blue)
10
VGA connector
11
Two USB 3.0 connectors
12
HDM dedicated network port (1Gb/s, RJ-45, default IP address 192.168.1.2/24)
13
OCP 3.0 network adapter (optional)

13
LEDs
Figure 11 Rear panel LEDs
Table 8 LEDs on the rear panel
LED
Status
UID LED
•Steady blue—UID LED is activated. The UID LED can be activated by
using the following methods:
Press the UID button LED.
Enable UID LED from HDM.
•Flashing blue:
1 Hz—The firmware is being upgraded or HDM is performing out-
of-band firmware update. Do not power off the server.
4 Hz—HDM is restarting. To restart HDM, press the UID button
LED for 8 seconds.
•Off—UID LED is not activated.
Link LED of the Ethernet port
•Steady green—A link is present on the port.
•Off—No link is present on the port.
Activity LED of the Ethernet
port
•Flashing green (1 Hz)—The port is receiving or sending data.
•Off—The port is not receiving or sending data.
Power supply LED
•Steady green—The power supply is operating correctly or the server
is in standby state.
•Flashing green (0.33 Hz)—The power supply is in standby state and
does not output power.
•Flashing green (2 Hz)—The power supply is updating its firmware.
•Steady amber—Either of the following conditions exists:
The power supply is faulty.
The power supply does not have power input, but another power
supply has correct power input.
•Flashing amber (1 Hz)—An alarm has occurred on the power supply.
•Off—No power supplies have power input, which can be caused by an
incorrect power cord connection or power source shutdown.
Ports
Table 9 Ports on the rear panel
Port
Type
Description
VGA connector
DB-15
Connects a display terminal, such as a monitor or
KVM device.
BIOS serial port
DB-9
The BIOS serial port is used for the following
purposes:
•Log in to the server when the remote network

14
Port
Type
Description
connection to the server has failed.
•Establish a GSM modem or encryption lock
connection.
NOTE:
For more information about the serial & DSD module,
see "Serial & DSD module."
USB connector
USB 3.0
Connects the following devices:
•USB flash drive.
•USB keyboard or mouse.
•USB optical drive for operating system
installation.
HDM dedicated
network port
RJ-45
Establishes a network connection to manage HDM
from its Web interface.
Power receptacle
Standard single-phase
Connects the power supply to the power source.
System board
System board components
Figure 12 System board components

15
Table 10 System board components
No.
Description
Mark
1
OCP 3.0 network adapter connector 2/DSD module
connector
OCP2&DSD&UART CARD
2
Server management module connector
BMC CON
3
TPM/TCM connector
TPM
4
PCIe riser connector 1 (for processor 1)
RISER1 PCIe x16
5
Fan connector for OCP 3.0 network adapter 1
OCP1 FAN
6
System battery
N/A
7
AUX connector for OCP 3.0 network adapter 1
OCP1 AUX
8
MCIO connector C1-P1A (for processor 1)
C1-P1A
9
MCIO connector C1-P1C (for processor 1)
C1-P1C
10
Drive backplane AUX connector 7
AUX 7
11
Drive backplane AUX connector 9
AUX 9
12
M.2 SSD AUX connector
M.2 AUX(FRONT)
13
Front I/O connector
RIGHT EAR
14
Drive backplane AUX connector 4
AUX 4
15
Power connector for OCP 3.0 network adapter 1
OCP1 PWR
16
LCD smart management module connector
DIAG LCD
17
MCIO connector C1-P0A (for processor 1)
C1-P0A
18
MCIO connector C1-P0C (for processor 1)
C1-P0C
19
MCIO connector C1-P2A (for processor 1)
C1-P2A
20
MCIO connector C1-P2C (for processor 1)
C1-P2C
21
Drive backplane power connector 3
PWR3
22
Drive backplane power connector 2
PWR2
23
Temperature sensor connector
AUX3
24
Drive backplane AUX connector 3
TEMP SENSE
25
Drive backplane AUX connector 1
AUX1
26
Drive backplane AUX connector 2
AUX2
27
MCIO connector C2-P0A (for processor 2)
C2-P0A
28
MCIO connector C2-P0C (for processor 2)
C2-P0C
29
MCIO connector C2-P2A (for processor 2)
C2-P2A
30
MCIO connector C2-P2C (for processor 2)
C2-P2C
31
Drive backplane power connector 1
PWR1
32
Front VGA and USB 3.0 connector
LEFT EAR
33
Chassis-open alarm module connector
INTRUDER
34
MCIO connector C2-P3A (for processor 2)
C2-P3A
35
Drive backplane power connector 5
PWR5

16
36
MCIO connector C2-P3C (for processor 2)
C2-P3C
37
Drive backplane power connector 8
PWR8
38
Drive backplane power connector 7
PWR7
39
Drive backplane AUX connector 5
AUX5
40
Liquid Leakage Detection module connector
LEAKDET
41
OCP 3.0 network adapter slot 2 (PCIe expansion connector)
OCP2 x8
42
PCIe riser connector 2 (for processor 2)
RISER2 PCIe x16
43
OCP3 AUX connector 8
AUX8(OCP/NCSI)
44
Drive backplane power connector 4
PWR4
45
Drive backplane power connector 6
PWR6
46
Drive backplane AUX connector 6
AUX6
47
LP SlimSAS connector C1-P4A (for processor 1)
C1-P4A
48
Embedded USB3.0 connector
INTER USB3.0
X
System maintenance switch
N/A
System maintenance switch
Figure 13 shows the system maintenance switch. Table 11 describes how to use the maintenance
switch.
Figure 13 System maintenance switch
Table 11 System maintenance switch description
Item
Description
Remarks
1
•Off (default)—HDM login requires the
username and password of a valid HDM
user account.
•On—HDM login requires the default
username and password.
For security purposes, turn off the switch after
you complete tasks with the default username
and password as a best practice.
5
•Off (default)—Normal server startup.
•On—Restores the default BIOS
To restore the default BIOS settings:
1. Power off the server, and turn on the

17
Item
Description
Remarks
settings.
switch.
2. Power on the switch and wait for a
minimum of 10 seconds.
3. Power off the server and then turn off the
switch.
4. Start the server and verify that the POST
screen prompts The CMOS defaults
were loaded.
CAUTION:
The server cannot start up when the switch is
turned on. To avoid service data loss, stop
running services and power off the server
before turning on the switch.
6
•Off (default)—Normal server startup.
•On—Clears all passwords from the
BIOS at server startup.
If this switch is on, the server will clear all the
passwords at each startup. Make sure you turn
off the switch before the next server startup if
you do not need to clear all the passwords.
2, 3, 4, 7,
and 8
Reserved for future use.
N/A
DIMM slots
The system board provides eight DIMM channels per processor, and 24 channels in total, as shown
in Figure 14. Each channel contains two DIMM slots.
Figure 14 System board DIMM slot layout