Asus Pro A520M-C II User manual

Motherboard
Pro A520M-C II

ii
E18277
First Edition
April 2021
Copyright© 2021 ASUSTeK COMPUTER INC. All Rights Reserved.
No part of this manual, including the products and software described in it, may be reproduced,
transmitted, transcribed, stored in a retrieval system, or translated into any language in any form or by any
means, except documentation kept by the purchaser for backup purposes, without the express written
permission of ASUSTeK COMPUTER INC. (“ASUS”).
Product warranty or service will not be extended if: (1) the product is repaired, modied or altered, unless
such repair, modication of alteration is authorized in writing by ASUS; or (2) the serial number of the
product is defaced or missing.
ASUS PROVIDES THIS MANUAL “AS IS” WITHOUT WARRANTY OF ANY KIND, EITHER EXPRESS
OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE IMPLIED WARRANTIES OR CONDITIONS OF
MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. IN NO EVENT SHALL ASUS, ITS
DIRECTORS, OFFICERS, EMPLOYEES OR AGENTS BE LIABLE FOR ANY INDIRECT, SPECIAL,
INCIDENTAL, OR CONSEQUENTIAL DAMAGES (INCLUDING DAMAGES FOR LOSS OF PROFITS,
LOSS OF BUSINESS, LOSS OF USE OR DATA, INTERRUPTION OF BUSINESS AND THE LIKE),
EVEN IF ASUS HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES ARISING FROM ANY
DEFECT OR ERROR IN THIS MANUAL OR PRODUCT.
SPECIFICATIONS AND INFORMATION CONTAINED IN THIS MANUAL ARE FURNISHED FOR
INFORMATIONAL USE ONLY, AND ARE SUBJECT TO CHANGE AT ANY TIME WITHOUT NOTICE,
AND SHOULD NOT BE CONSTRUED AS A COMMITMENT BY ASUS. ASUS ASSUMES NO
RESPONSIBILITY OR LIABILITY FOR ANY ERRORS OR INACCURACIES THAT MAY APPEAR IN THIS
MANUAL, INCLUDING THE PRODUCTS AND SOFTWARE DESCRIBED IN IT.
Products and corporate names appearing in this manual may or may not be registered trademarks or
copyrights of their respective companies, and are used only for identication or explanation and to the
owners’ benet, without intent to infringe.

iii
Contents
Safety information...................................................................................................... iv
About this guide.......................................................................................................... v
Package contents....................................................................................................... vi
Pro A520M-C II specifications summary.................................................................. vi
Chapter 1 Product Introduction
1.1 Before you proceed...................................................................................... 1-1
1.2 Motherboard overview .................................................................................1-1
1.3 Central Processing Unit (CPU).................................................................... 1-8
1.4 System memory............................................................................................ 1-9
Chapter 2 BIOS Information
2.1 BIOS Setup program ....................................................................................2-1
2.2 BIOS menu screen........................................................................................2-2
2.3 Event Log ......................................................................................................2-3
2.4 Exit menu ......................................................................................................2-4
Appendix
Notices ..................................................................................................................... A-1
Warranty................................................................................................................... A-6
ASUS contact information...................................................................................... A-8

iv
Safety information
Electrical safety
• To prevent electrical shock hazard, disconnect the power cable from the electrical outlet
before relocating the system.
• When adding or removing devices to or from the system, ensure that the power cables
for the devices are unplugged before the signal cables are connected. If possible,
disconnect all power cables from the existing system before you add a device.
• Before connecting or removing signal cables from the motherboard, ensure that all power
cables are unplugged.
• Seek professional assistance before using an adapter or extension cord. These devices
could interrupt the grounding circuit.
• Ensure that your power supply is set to the correct voltage in your area. If you are not
sure about the voltage of the electrical outlet you are using, contact your local power
company.
• If the power supply is broken, do not try to x it by yourself. Contact a qualied service
technician or your retailer.
Operation safety
• Before installing the motherboard and adding components, carefully read all the manuals
that came with the package.
• Before using the product, ensure all cables are correctly connected and the power cables
are not damaged. If you detect any damage, contact your dealer immediately.
• To avoid short circuits, keep paper clips, screws, and staples away from connectors,
slots, sockets and circuitry.
• Avoid dust, humidity, and temperature extremes. Do not place the product in any area
where it may be exposed to moisture.
• Place the product on a stable surface.
• If you encounter technical problems with the product, contact a qualied service
technician or your retailer.
• Your motherboard should only be used in environments with ambient temperatures
between 0°C and 40°C.

v
About this guide
This user guide contains the information you need when installing and conguring the
motherboard.
How this guide is organized
This guide contains the following parts:
• Chapter 1: Product Introduction
This chapter describes the features of the motherboard and the new technology it
supports. It includes descriptions of the switches, jumpers, and connectors on the
motherboard.
• Chapter 2: BIOS Information
This chapter tells how to boot into the BIOS.
Where to find more information
Refer to the following sources for additional information and for product and software
updates.
1. ASUS website
The ASUS website provides updated information on ASUS hardware and software
products. Refer to the ASUS contact information.
2. Optional documentation
Your product package may include optional documentation, such as warranty flyers,
that may have been added by your dealer. These documents are not part of the
standard package.
Conventions used in this guide
To ensure that you perform certain tasks properly, take note of the following symbols used
throughout this manual.
CAUTION: Information to prevent damage to the components and injuries to
yourself when trying to complete a task.
IMPORTANT: Instructions that you MUST follow to complete a task.
NOTE: Tips and additional information to help you complete a task.

vi
Pro A520M-C II specifications summary
CPU
AMD AM4 Socket for AMD Ryzen™ 5000 Series/ 4000 G-Series/ 3000 Series
Desktop Processors*
* Refer to www.asus.com for CPU support list.
Chipset AMD A520 Chipset
Memory
2 x DIMM, Max. 64GB, DDR4 4600(OC)/4400(OC)/4133(OC)/4000(OC)/
3866(OC)/3733(OC)/3600(OC)/3466(OC)/3333(OC)/3200/3000/2800/2666/
2400/2133 MHz, Un-buffered Memory*
Dual Channel Memory Architecture
* ECC memory (ECC mode) support varies by CPU types.
* Refer to www.asus.com for the Memory QVL (Qualified Vendors Lists), and memory
frequency support depends on the CPU types.
Graphics
1 x DisplayPort
1 x D-Sub
1 x DVI-D
1 x HDMI™ 2.1 (4K@60Hz)
* Graphics specifications may vary between CPU types.
* The DVI-D port and the DisplayPort cannot work at the same time. Only the DVI-D
port functions when the two ports are both connected.
Expansion Slots
AMD Ryzen™ 5000 Series/ 4000 G-Series/ 3000 Series Desktop Processors
1 x PCIe 3.0 x16 slot (supports x16 mode)
AMD A520 Chipset
2 x PCIe 3.0 x1 slots
1 x PCI slot
Storage
Total supports 1 x M.2 slot and 4 x SATA 6Gb/s ports
AMD Ryzen™ 5000 Series/ 4000 G-Series/ 3000 Series Desktop Processors
M.2 slot (Key M), type 2242/2260/2280 (supports PCIe 3.0 x4 & SATA modes)
AMD A520 Chipset
4 x SATA 6Gb/s ports
Supports RAID 0, 1, and 10
Ethernet 1 x Realtek 1Gb Ethernet
ASUS LANGuard
(continued on the next page)
Package contents
Check your motherboard package for the following items.
Motherboard 1 x Pro A520M-C II motherboard
Cables 2 x SATA 6Gb/s cables
Miscellaneous 1 x I/O Shield
1 x M.2 SSD screw package
Application DVD 1 x Support DVD
Documentation 1 x ACC Express Activation Key card
1 x User manual
If any of the above items is damaged or missing, contact your retailer.

vii
Pro A520M-C II specifications summary
USB
Rear USB (Total 6 ports)
4 x USB 3.2 Gen 1 ports (4 x Type-A)
2 x USB 2.0 ports (2 x Type-A)
Front USB (Total 6 ports)
1 x USB 3.2 Gen 1 header supports additional 2 USB 3.2 Gen 1 ports
2 x USB 2.0 headers support additional 4 USB 2.0 ports
Audio
Realtek ALC897 7.1 Surround Sound High Definition Audio CODEC*
- Supports: Jack detection, Multi-streaming, Front Panel Jack-retasking
- Supports up to 24-Bit/192 kHz playback
* A chassis with an HD audio module in the front panel is required to support 7.1
Surround Sound audio output.
Back Panel I/O Ports
4 x USB 3.2 Gen 1 ports (4 x Type-A)
2 x USB 2.0 ports (2 x Type-A)
1 x DisplayPort
1 x D-Sub port
1 x DVI-D port
1 x HDMITM port
1 x Realtek 1Gb Ethernet port
3 x Audio jacks
1 x COM port
1 x PS/2 Keyboard (purple) port
1 x PS/2 Mouse (green) port
Internal I/O
Connectors
Fan and Cooling related
1 x 4-pin CPU Fan header
2 x 4-pin Chassis Fan headers
Power related
1 x 24-pin Main Power connector
1 x 8-pin +12V Power connector
Storage related
1 x M.2 slot (Key M)
4 x SATA 6Gb/s ports
USB
1 x USB 3.2 Gen 1 header supports additional 2 USB 3.2 Gen 1 ports
2 x USB 2.0 headers support additional 4 USB 2.0 ports
Miscellaneous
1 x Clear CMOS header
1 x Chassis Intrusion header
1 x COM Port header
1 x Front Panel Audio header (AAFP)
1 x LPC debug header
1 x LPT header
1 x SMBUS header
1 x Speaker header
1 x 10-1 pin System Panel header
(continued on the next page)

viii
Pro A520M-C II specifications summary
Special Features
ASUS Q-Design
- ASUS Q-DIMM
- ASUS Q-Slot
ASUS Thermal Solution
- Aluminum heatsink design
ASUS EZ DIY
- Box Headers
Bespoke Motherboard Design & Business Focused Features
- ASUS Self Recovering BIOS
- ASUS Event Log
- ASUS Commercial BIOS kit
- Anti-Moisture Coating
- 24/7 Reliability
- Overcurrent Protection
TPM 2.0 IC Onboard
Software Features
ASUS Exclusive Software
IT Management software supported
- ASUS Control Center Express (ACCE)
BIOS 128 Mb Flash ROM, UEFI AMI BIOS
Manageability WOL by PME, PXE
Operating System Windows® 10 64-bit
Form Factor mATX Form Factor
9.6 inch x 9.0 inch (24.4 cm x 22.9 cm)
Specications are subject to change without notice. Refer to the ASUS website for the
latest specications.

ASUS Pro A520M-C II 1-1
USB56USB34
DDR4 DIMM_A1* (64bit, 288-pin module) DDR4 DIMM_B1* (64bit, 288-pin module)
DIGI+
VRM
CPU_FAN
CHA_FAN2
CHA_FAN1
DP
HDMI
COM2
U32G1_3~6
LAN_USB12
KBMS
DVI
VGA
AUDIO
LPC_DEBUG
F_PANEL
AAFP
SPEAKER
SATA6G_4
CLRTC
SATA6G_3SATA6G_2
SATA6G_1
128Mb
BIOS TPM
EATX12V
EATXPWR
U32G1_12
AMD
A520
BATTERY
Super
I/O
PCIEX1_1
PCIEX1_2 ASM
1083
PCI
M.2(SOCKET3)
2280 2260 2242
PCIEX16
COM1 LPT
22.9cm(9.0in)
24.4cm(9.6in)
SOCKET AM4
Ethernet
Audio
Codec CHASSIS
SMBUS
7
8
6
5
13 1012 15 11
3
5 1 24 4
7 1618179
14
Product Introduction
1
1.1 Before you proceed
Take note of the following precautions before you install motherboard components or change
any motherboard settings.
• Unplug the power cord from the wall socket before touching any component.
• Before handling components, use a grounded wrist strap or touch a safely grounded
object or a metal object, such as the power supply case, to avoid damaging them due
to static electricity.
• Before you install or remove any component, ensure that the ATX power supply is
switched off or the power cord is detached from the power supply. Failure to do so
may cause severe damage to the motherboard, peripherals, or components.
Unplug the power cord before installing or removing the motherboard. Failure to do so can
cause you physical injury and damage motherboard components.
1.2 Motherboard overview
Place this side
towards the rear
of the chassis

1-2 Chapter 1: Product Introduction
1.2.1 Layout contents
1. CPU socket
The motherboard comes with an AMD Socket AM4 designed for AMD Ryzen™ 5000 Series/
4000 G-Series/ 3000 Series Desktop Processors.
For more details, refer to 1.3 Central Processing Unit (CPU).
2. DDR4 DIMM slots
The motherboard comes with Dual Inline Memory Modules (DIMM) slots designed for DDR4
(Double Data Rate 4) memory modules.
For more details, refer to 1.4 System memory.
3. Expansion slots
This motherboard supports one PCIe 3.0 x16 graphics card and two PCIe 3.0 x1 network
cards, SCSI cards and other cards that comply with the PCI Express specication.
The PCI slot supports a card such as a LAN card, SCSI card, USB card, or any other card
that complies with PCI specications.
4. Fan headers
The Fan headers allow you to connect fans to cool the system.
5. Power connectors
These Power connectors allow you to connect your motherboard to a power supply. The
power supply plugs are designed to t in only one orientation. Find the proper orientation and
push down rmly until the power supply plugs are fully inserted.
Ensure to connect the 8-pin power plug.
• For a fully congured system, we recommend that you use a power supply unit
(PSU) that complies with ATX 12V Specication 2.0 (or later version) and provides a
minimum power of 350W.
• We recommend that you use a PSU with a higher power output when conguring a
system with more power-consuming devices. The system may become unstable or
may not boot up if the power is inadequate.
• If you are uncertain about the minimum power supply requirement for your system, we
recommend you to refer to online resources for Power Supply Wattage Calculator.
GND FAN PWR FAN IN FAN PWM
FAN PWM
FAN IN
FAN PWR
GND

ASUS Pro A520M-C II 1-3
6. M.2 slot (Key M)
The M.2 slot allows you to install an M.2 device such as an M.2 SSD module.
The M.2 slot supports a PCIe 3.0 x4 mode and SATA mode M Key design and type
2242/2260/2280 storage device.
7. SATA 6Gb/s ports
The SATA 6Gb/s ports allow you to connect SATA devices such as optical disc drives and
hard disk drives via SATA cables.
8. USB 3.2 Gen 1 header
The USB 3.2 Gen 1 header allows you to connect a USB 3.2
Gen 1 module for additional USB 3.2 Gen 1 ports. The USB 3.2
Gen 1 header provides data transfer speed of up to 5 Gb/s.
The USB 3.2 Gen 1 module is purchased separately.
9. USB 2.0 heades
The USB 2.0 headers allow you to connect USB modules for additional USB 2.0
ports. The USB 2.0 headers provide data transfer speeds of up to 480 Mb/s.
DO NOT connect a 1394 cable to the USB connectors. Doing so will
damage the motherboard!
The USB 2.0 modules are purchased separately.
10. Chassis intrusion header
This header is for a chassis-mounted intrusion detection sensor or switch.
Connect one end of the chassis intrusion sensor or switch cable to this
header. The chassis intrusion sensor or switch sends a high-level signal to
this header when a chassis component is removed or replaced. The signal
is then generated as a chassis intrusion event.
USB3+5V
IntA_P1_SSRX-
IntA_P1_SSRX+
GND
IntA_P1_SSTX-
IntA_P1_SSTX+
GND
IntA_P1_D-
IntA_P1_D+
GND
PIN 1
USB3+5V
IntA_P2_SSRX-
IntA_P2_SSRX+
GND
IntA_P2_SSTX-
IntA_P2_SSTX+
GND
IntA_P2_D-
IntA_P2_D+
PIN 1
USB+5V USB_P3- USB_P3+ GND NC
USB+5V
USB_P4-
USB_P4+
GND
CHASSIS
+5VSB_MB Chassis Signal GND
PIN 1

1-4 Chapter 1: Product Introduction
11. Clear CMOS header
This header allows you to clear the CMOS RTC RAM data of the system setup
information such as date, time, and system passwords.
To erase the RTC RAM:
1. Turn OFF the computer and unplug the power cord.
2. Use a metal object such as a screwdriver to short the two pins.
3. Plug the power cord and turn ON the computer.
4. Hold down the <Del> key during the boot process and enter BIOS Setup to re-
enter data.
If the steps above do not help, remove the onboard battery and short the two pins again to
clear the CMOS RTC RAM data. After clearing the CMOS, reinstall the battery.
12. COM Port header
This header is for a serial (COM) port. Connect the serial port module cable to
this header, then install the module to a slot opening at the back of the system
chassis.
13. Front panel audio header
This header is for a chassis-mounted front panel audio I/O module that
supports HD audio standard. Connect one end of the front panel audio I/O
module cable to this header.
• We recommend that you connect a high-denition front panel
audio module to this header to avail of the motherboard’s high-
denition audio capability.
• If you want to connect a high-denition front panel audio module
to this header, set the Front Panel Type item in the BIOS Setup to
[HD Audio]. By default, this header is set to [HD Audio].
14. LPC Debug header
This header allows connection to a LPC Debug card.
• Scan the QR code to view the meaning of
each debugging code.
• Debugging codes are only available for
ASUS LPC Debug cards.
• Contact your region sales representative
for LPC Debug cards ordering.
CLRTC
+3V_BAT GND
PIN 1
COM
PIN 1
DCD
TXD
GND
RTS
RI
RXD
DTR
DSR
CTS
AAFP
AGND NC SENSE1_RETUR SENSE2_RETUR
PORT1 L
PORT1 R PORT2 R
SENSE_SEND
PORT2 L
HD-audio-compliant
pin definition
PIN 1
+3V +3V CK_24M_LPC GND
S_LAD0 S_LAD1 S_LAD2 S_LAD3
S_LFRAME#
LPC_DEBUG

ASUS Pro A520M-C II 1-5
15. LPT header
The LPT (Line Printing Terminal) header supports devices such
as a printer. LPT standardizes as IEEE 1284, which is the parallel
port interface on IBM PC-compatible computers.
16. System Management Bus header
The System Management Bus (SMBus) connector allows you to connect a
SMBus device. This connector is generally used for communication with the
system and power management-related tasks.
17. Speaker header
The 4-pin header is for the chassis-mounted system warning speaker. The
speaker allows you to hear system beeps and warnings.
18. 10-1 pin System panel header
This header supports several chassis-mounted functions.
• System power LED (2-pin +PWR_LED-)
This 2-pin header is for the system power LED. Connect the chassis
power LED cable to this header. The system power LED lights up
when you turn on the system power, and blinks when the system is
in sleep mode.
• Hard disk drive activity LED (2-pin +HDD_LED-)
This 2-pin header is for the HDD Activity LED. Connect the HDD
Activity LED cable to this header. The HDD LED lights up or flashes
when data is read from or written to the HDD.
• Power button/Soft-off button (2-pin PWR_BTN)
This header is for the system power button.
• Reset button (2-pin RESET)
This 2-pin header is for the chassis-mounted reset button for system reboot without
turning off the system power.
PIN 1
O_LPT_XSTB#_R
O_LPT_XPD0_R O_LPT_XPD1_R O_LPT_XPD2_R O_LPT_XPD3_R O_LPT_XPD4_R O_LPT_XPD5_R O_LPT_XPD6_R O_LPT_XPD7_R O_LPT_ACK#_R
O_LPT_BUSY_R
O_LPT_PE_R
O_LPT_SLCT_R
O_LPT_XAFD#_R O_LPT_ERROR#_R O_LPT_XINIT#_R O_LPT_XSLIN#_R GND GND GND GND GND GND GND GND
SMBUS
GND SMBUS_CLKSMBUS_DATA
PIN 1
SPEAKER
+5V GND GND Speaker Out
PIN 1
F_PANEL
PIN 1
PWR_LED+ PWR_LED- PWR GND
HDD_LED+
HDD_LED-
Ground
HWRST#
(NC)
PWR_BTN+PWR_LED-
+HDD_LED- RESET

1-6 Chapter 1: Product Introduction
1.2.2 Rear panel connectors
1
2
8
910 11
12 13
5
34
6 7
1. PS/2 Mouse port (green). This port is for a PS/2 mouse.
2. Video Graphics Adapter (VGA) port. This 15-pin port is for a VGA monitor or other
VGA-compatible devices.
3. Serial port (COM). This port connects a modem, or other devices that conform with
serial specication.
4. USB 3.2 Gen 1 (up to 5Gbps) ports. These 9-pin Universal Serial Bus (USB) ports
connect to USB 3.2 Gen 1 devices.
5. Ethernet port. This port allows Gigabit connection to a Local Area Network (LAN)
through a network hub. Refer to the table below for the Ethernet port LED indications.
Ethernet port LED indications
Ethernet port
Speed
LED
Activity Link
LED
Activity/Link LED Speed LED
Status Description Status Description
OFF No link OFF 10 Mbps connection
ORANGE Linked ORANGE 100 Mbps connection
BLINKING Data activity GREEN 1 Gbps connection
6. Line In port (light blue). This port connects the tape, CD, DVD player, or other audio
sources.
7. Line Out port (lime). This port connects a headphone or a speaker. In 4, 5.1, and
7.1-channel congurations, the function of this port becomes Front Speaker Out.
8. PS/2 Keyboard port (purple). This port is for a PS/2 keyboard.
9. DVI-D port. This port is for any DVI-D compatible device.
DVI-D can not be converted to output from RGB Signal to CRT and is not compatible with
DVI-I.
10. DisplayPort. This port is for a DisplayPort-compatible device.

ASUS Pro A520M-C II 1-7
11. HDMI™ port. This port is for a High-Denition Multimedia Interface (HDMI™)
connector, and is HDCP compliant allowing playback of HD DVD, Blu-ray, and other
protected content.
12. USB 2.0 ports. These 4-pin Universal Serial Bus (USB) ports are for USB 2.0 devices.
13. Microphone port (pink). This port connects a microphone.
Refer to the audio conguration table below for the function of the audio ports in 2, 4, 5.1,
or 7.1-channel conguration.
Audio 2, 4, 5.1 or 7.1-channel configuration
Port Headset
2-channel 4-channel 5.1-channel 7.1-channel
Light Blue (Rear panel) Line In Rear Speaker Out Rear Speaker Out Rear Speaker Out
Lime (Rear panel) Line Out Front Speaker Out Front Speaker Out Front Speaker Out
Pink (Rear panel) Mic In Mic In Bass/Center Bass/Center
Lime (Front panel) — — — Side Speaker Out*/
Headphone
Pink (Front panel) — — — Mic In*/
Side Speaker Out
* Multi-streaming is disabled by default, and the Lime (front panel) jack may be used as Side Speaker Out. If multi-
streaming is enabled, the Lime (front panel) jack will support headphone, and Pink (front panel) jack will support
Side Speaker Out.
To configure a 7.1-channel audio output:
Use a chassis with HD audio module in the front panel to support a 7.1-channel audio
output.

1-8 Chapter 1: Product Introduction
1.3 Central Processing Unit (CPU)
This motherboard comes with an AMD Socket AM4 designed for
AMD Ryzen™ 5000 Series/ 4000 G-Series/ 3000 Series Desktop
Processors.
Unplug all power cables before installing the CPU.
The AM4 socket has a different pinout design. Ensure that you use a CPU designed for the
AM4 socket. The CPU ts in only one correct orientation. DO NOT force the CPU into the
socket to prevent bending the connectors on the socket and damaging the CPU!
Installing the CPU
Apply the Thermal Interface Material to the CPU heatsink and CPU before you install the
heatsink and fan if necessary.
1
2
3
4
5
6
7
8
9
12
13
11
8
10
14
15
1
2
3
4
5
6
7
8
9
12
13
11
8
10
14
15
1
2
3
4
5
6
7
8
9
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11
8
10
14
15
1
2
3
4
5
6
7
8
9
12
13
11
8
10
14
15

ASUS Pro A520M-C II 1-9
1.4 System memory
This motherboard comes with two Double Data Rate 4 (DDR4) Dual Inline Memory Module
(DIMM) sockets. The gure illustrates the location of the DDR4 DIMM sockets:
DIMM_B1*
DIMM_A1*
Channel Sockets
Channel A DIMM_A1*
Channel B DIMM_B1*
• You may install varying memory sizes in Channel A and Channel B. The system
maps the total size of the lower-sized channel for the dual-channel conguration. Any
excess memory from the higher-sized channel is then mapped for single-channel
operation.
• Always install DIMMs with the same CAS latency. For optimal compatibility, we
recommend that you install memory modules of the same version or date code (D/C)
from the same vendor. Check with the retailer to get the correct memory modules.
• A DDR4 memory module is notched differently from a DDR, DDR2, or DDR3 module.
DO NOT install a DDR, DDR2, or DDR3 memory module to the DDR4 slot.
• The default memory operation frequency is dependent on its Serial Presence Detect
(SPD), which is the standard way of accessing information from a memory module.
Under the default state, some memory modules for overclocking may operate at a
lower frequency than the vendor-marked value.
• For system stability, use a more efcient memory cooling system to support a full
memory load.
• ECC memory (ECC mode) support varies by CPU types.
• Refer to www.asus.com for the latest Memory QVL (Qualied Vendors Lists), and
memory frequency support depends on the CPU types.
Recommended memory configurations
DIMM_A1*
DIMM_B1*
DIMM_B1* DIMM_A1*

1-10 Chapter 1: Product Introduction
Installing a DIMM
1 2
B
A
A
To remove a DIMM
B
A

BIOS Information
2
ASUS Self-Recovering BIOS
ASUS-exclusive BIOS protection technology automatically recovers the system’s BIOS with
a veried backup in the event of an update failure, preventing the need to replace or reinstall
your hardware.
• Ensures safe BIOS updates.
• Requires no additional software.
• Provides automatic update failure detection and recovery.
• Reduces maintenance frequency and costs.
The system will automatically activate ASUS Self-Recovering BIOS after reboot from the
BIOS update failure.
2.1 BIOS Setup program
Use the BIOS Setup program to update the BIOS or congure its parameters. The BIOS
screens include navigation keys and brief online help to guide you in using the BIOS Setup
program.
Entering BIOS Setup at startup
Press <Delete> or <F2> during the Power-On Self Test (POST). If you do not press <Delete>
or <F2>, POST continues with its routines.
Entering BIOS Setup after POST
• Press <Ctrl>+<Alt>+<Del> simultaneously.
• Press the reset button on the system chassis.
• Press the power button to turn the system off then back on. Do this option only if you
failed to enter BIOS Setup using the rst two options.
Using the power button, reset button, or the <Ctrl>+<Alt>+<Del> keys to force reset from a
running operating system can cause damage to your data or system. We recommend you
always shut down the system properly from the operating system.
• The BIOS Setup screens shown in this section are for reference purposes only, and
may not exactly match what you see on your screen.
• Visit the ASUS website at www.asus.com to download the latest BIOS le for this
motherboard.
• If the system becomes unstable after changing any BIOS setting, load the default
settings to ensure system compatibility and stability. Select the Load Optimized
Defaults item under the Exit menu or press hotkey <F5>.
• If the system fails to boot after changing any BIOS setting, try to clear the CMOS and
reset the motherboard to the default value. See section 1.2 Motherboard overview
for information on how to erase the RTC RAM.
ASUS Pro A520M-C II 2-1

2.2 BIOS menu screen
Menu bar
Menu items
General Help
Configuration fieldsSub-menu item
2-2 Chapter 2: BIOS Information