Asus Prime B660M-AJ D4 User manual

Motherboard
PRIME B660M-AJ D4

ii
E19241
First Edition
September 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
PRIME B660M-AJ D4 specications 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.......................................................................................... 1-10
1.5 M.2 installation............................................................................................ 1-12
Chapter 2 BIOS and RAID Support
2.1 Knowing BIOS............................................................................................... 2-1
2.2 BIOS Setup program .................................................................................... 2-2
2.3 ASUS EZ Flash 3........................................................................................... 2-3
2.4 ASUS CrashFree BIOS 3.............................................................................. 2-4
2.5 RAID congurations..................................................................................... 2-5
Appendix
Notices ..................................................................................................................... A-1
Warranty................................................................................................................... A-6
ASUS contact information...................................................................................... A-8
Service and Support ............................................................................................... 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 and RAID Support
This chapter tells how to boot into the BIOS, upgrade BIOS using the EZ Flash Utility
and support on RAID.
Where to nd 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
PRIME B660M-AJ D4 specications summary
CPU
Intel®Socket LGA1700 for 12th Gen Intel®Core™, Pentium®Gold and
Celeron®Processors*
Supports Intel®Turbo Boost Technology 2.0 and Intel®Turbo Boost Max
Technology 3.0**
* Refer to www.asus.com for CPU support list.
** Intel®Turbo Boost Max Technology 3.0 support depends on the CPU types.
Chipset Intel®B660 Chipset
Memory
4 x DIMM, Max. 128GB, DDR4 5333(OC)/5000(OC)/4800(OC)/4600(OC)/
4400(OC)/4266(OC)/4000(OC)/3733(OC)/3600(OC)/3466(OC)/3400(OC)/
3333(OC)/3200/3000/2933/2800/2666/2400/2133
Non-ECC, Un-buffered Memory*
Dual Channel Memory Architecture
Supports Intel® Extreme Memory Prole (XMP)
OptiMem II
* Actual Memory data rate depends on the CPU types and DRAM modules, for more
information refer to www.asus.com for the Memory QVL (Qualied Vendors Lists).
Graphics
1 x DisplayPort**
2 x HDMI®ports***
* Graphics specications may vary between CPU types. Please refer to
www.intel.com for any updates.
** Support max. 4K@60Hz as specied in DisplayPort 1.4.
*** Support 4K@60Hz as specied in HDMI
®
2.1.
Expansion Slots
Intel®12th Gen Processors
1 x PCIe 4.0/3.0 x16 slot
Intel®B660 Chipset*
1 x PCIe 3.0 x16 slot (supports x4 mode)
1 x PCIe 3.0 x1 slot
* Supports Intel
®
Optane Memory H Series on PCH-attached PCIe slot.
(continued on the next page)
Package contents
Check your motherboard package for the following items.
Motherboard 1 x PRIME B660M-AJ D4 motherboard
Cables 2 x SATA 6Gb/s cables
Miscellaneous
1 x I/O Shield
1 x M.2 Rubber Package
1 x M.2 SSD screw package
Application DVD 1 x Support DVD
Documentation 1 x User Guide
If any of the above items is damaged or missing, contact your retailer.

vii
PRIME B660M-AJ D4 specications summary
Storage
Total supports 2 x M.2 slots and 4 x SATA 6Gb/s ports*
Intel® 12th Gen Processors
M.2_1 slot (Key M), type 2242/2260/2280
- Intel®12th Gen processors support PCIe 4.0 x4 mode
Intel®B660 Chipset**
M.2_2 slot (Key M), type 2242/2260/2280 (supports PCIe 4.0 x4 mode)
4 x SATA 6Gb/s ports
* Intel®Rapid Storage Technology supports SATA RAID 0/1/5/10.
** Intel®Rapid Storage Technology supports Intel®Optane Memory H Series on
PCH attached M.2 slots.
Ethernet 1 x Intel®1Gb Ethernet
Wireless & Bluetooth V-M.2 slot only (Key E, CNVi & PCIe)*
*Wi-Fi module is sold separately.
USB
Rear USB (Total 6 ports)
2 x USB 3.2 Gen 2 ports (2 x Type-A )
4 x USB 2.0 ports (4 x Type-A)
Front USB (Total 7 ports)
2 x USB 3.2 Gen 1 headers support additional 4 USB 3.2 Gen 1 ports
1 x USB 2.0 header supports additional 2 USB 2.0 ports
1 x USB 2.0 header supports additional 1 USB 2.0 port
Audio
Realtek 7.1 Surround Sound High Denition Audio CODEC*
- Supports: Jack detection, Multi-streaming, Front Panel Jack-retasking
- Supports up to 24-Bit/192kHz playback
Audio Features
- Audio Shielding
- Premium audio capacitors
- Dedicated audio PCB layers
* 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
2 x USB 3.2 Gen 2 ports (2 x Type-A)
4 x USB 2.0 ports (4 x Type-A)
1 x DisplayPort
2 x HDMI®ports
1 x V-M.2 slot (Key E)
1 x Intel®1Gb Ethernet port
3 x Audio jacks
1 x PS/2 Keyboard/Mouse combo port
Internal I/O
Connectors
Fan and cooling related
1 x 4-pin CPU Fan header
1 x 4-pin CPU OPT 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
(continued on the next page)

viii
PRIME B660M-AJ D4 specications summary
Internal I/O
Connectors
Storage related
2 x M.2 slots (Key M)
4 x SATA 6Gb/s ports
USB
2 x USB 3.2 Gen 1 headers support additional 4 USB 3.2 Gen 1 ports
1 x USB 2.0 header supports additional 2 USB 2.0 ports
1 x USB 2.0 header supports additional 1 USB 2.0 port
Miscellaneous
2 x Addressable Gen 2 headers
2 x AURA RGB headers
1 x Clear CMOS header
1 x COM Port header
1 x Front Panel Audio header (AAFP)
1 x LPT header
1 x S/PDIF Out header
1 x SPI TPM header (14-1pin)
1 x 20-3 pin System Panel header with Chassis intrude function
Special Features
ASUS 5X PROTECTION III
- DIGI+ VRM
- Enhanced DRAM Overcurrent Protection
- ESD Guards
- LANGuard
- Overvoltage Protection
- SafeSlot Core+
- Stainless-Steel Back I/O
ASUS Q-Design
- Q-DIMM
- Q-Slot
ASUS Thermal Solution
- M.2 heatsink
- VRM heatsink design
ASUS EZ DIY
- ProCool
AURA Sync
- AURA RGB headers
- Addressable Gen 2 headers
Software Features
ASUS Exclusive Software
Armoury Crate
- AURA Creator
- AURA Sync
- Fan Xpert 2+
(continued on the next page)

ix
PRIME B660M-AJ D4 specications summary
Software Features
AI Suite 3
- Performance And Power Saving Utility
TurboV EVO
EPU
DIGI+ VRM
ASUS CPU-Z
Norton Anti-virus software (Free Trial version)
WinRAR
UEFI BIOS
ASUS EZ DIY
- ASUS CrashFree BIOS 3
- ASUS EZ Flash 3
- ASUS UEFI BIOS EZ Mode
BIOS 128Mb Flash ROM, UEFI AMI BIOS
Manageability WOL by PME, PXE
Operating System Windows®11 64-bit
Windows®10 64-bit
Software Features mATX Form Factor
9.6 inch x 9.6 inch (24.4 cm x 24.4 cm)
Specications are subject to change without notice. Refer to the ASUS website for the
latest specications.

x

1-1
1
PRIME B660M-AJ D4
Product Introduction
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
DDR4 DIMM_A1 (64bit, 288-pin module) DDR4 DIMM_A2 (64bit, 288-pin module) DDR4 DIMM_B1 (64bit, 288-pin module) DDR4 DIMM_B2 (64bit, 288-pin module)
DIGI+
VRM
CHA_FAN2
CPU_FAN CPU_OPT
CHA_FAN1
LPT
COM_DEBUG
RGB_HEADER2RGB_HEADER1
PANEL
AAFP COM
SPDIF_OUT CLRTC
TPM SATA6G
_34
SATA6G_1 SATA6G_2
128Mb
BIOS
ATX_12V
ATX_PWR
U32G1_910
U32G1_34
LAN_USB_E12
HDMI1
_DP
HDMI2
BATTERY
KBMS
_USB
_E34
Intel
Ethernet
Super
I/O
M.2_1(SOCKET3)
M.2_2(SOCKET3)
2280 2260 2242
AURA
228022602242
PCIEX16(G3)
PCIEX1(G3)
PCIEX16(G4)
USB_7 USB_56
24.4cm(9.6in)
24.4cm(9.6in)
Intel®
B660
M.2_2(SOCKET3)
PCIE SATA Optane Memory
4.0 X4 X V
M.2_1(SOCKET3)
PCIE SATA
4.0 X4 X
Audio
CODEC
ADD GEN 2_2 ADD GEN 2_1
LGA1700
AUDIO
M.2(WIFI)
U32G2_12
8
6
19
7
5
10
916 814 1315 18
3
5 1 2 4
7 20
12
4
17
6
4
11
The pin denitions in this chapter are for reference only. The pin names depend on the
location of the header/jumper/connector.

1-2
1.2.1 Layout contents
1. CPU socket
The motherboard comes with a surface mount Intel®Socket LGA1700 designed for 12th Gen
Intel®Core™, Pentium®Gold and Celeron®Processors.
For more details, refer to 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 System memory.
3. Expansion slots
This motherboard supports one PCIe x16 graphics card, one PCIe x16 (supporting x4 mode)
and one PCIe x1 network cards, SCSI cards and other cards that comply with the PCI
Express specication.
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.
• 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.
• If you want to use two or more high-end PCI Express x16 cards, use a PSU with
1000W power or above to ensure the system stability.
6. M.2 slots (Key M)
The M.2 slots allow you to install M.2 devices such as M.2 SSD modules.
• Intel®12th Gen Processors
M.2_1 slot (Key M), type 2242/2260/2280
- Intel®12th processors support PCIe 4.0 x4 mode
• Intel®B660 Chipset
M.2_2 slot (Key M), type 2242/2260/2280 (supports PCIe 4.0 x4 mode)
GND FAN PWR FAN IN FAN PWM
FAN PWM
FAN IN
FAN PWR
GND
FAN PWM
FAN IN
FAN PWR
GND
Chapter 1: Product Introduction

1-3
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 headers
The USB 3.2 Gen 1 headers allow you to connect a USB 3.2 Gen
1 module for additional USB 3.2 Gen 1 ports. The USB 3.2 Gen 1
headers provide data transfer speeds of up to 5 Gb/s.
The USB 3.2 Gen 1 module is purchased separately.
9. USB 2.0 headers
The USB 2.0 headers allow you to connect a USB module 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 module is purchased separately.
10. Addressable Gen 2 headers
The Addressable Gen 2 headers allow you to connect individually addressable
RGB WS2812B LED strips or WS2812B based LED strips.
The Addressable Gen 2 headers support WS2812B addressable RGB LED strips (5V/Data/
Ground), with a maximum power rating of 3A (5V), and the addressable headers on this
board can handle a combined maximum of 500 LEDs.
Before you install or remove any component, ensure that the 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.
• Actual lighting and color will vary with LED strip.
• If your LED strip does not light up, check if the addressable RGB LED strip is
connected in the correct orientation, and the 5V connector is aligned with the 5V
header on the motherboard.
• The addressable RGB LED strip will only light up when the system is powered on.
• The addressable RGB LED strip is purchased separately.
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_P1- USB_P1+ GND NC
USB+5V
USB_P2-
USB_P2+
GND
ADD_GEN 2
+5V
Data
Ground
PIN 1
PRIME B660M-AJ D4

1-4
11. AURA RGB headers
The RGB headers allow you to connect RGB LED strips.
The RGB headers support 5050 RGB multi-color LED strips (12V/G/R/B), with a maximum
power rating of 3A (12V), and no longer than 3m.
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.
• Actual lighting and color will vary with LED strip.
• If your LED strip does not light up, check if the RGB LED extension cable and the
RGB LED strip are connected in the correct orientation, and the 12V connector is
aligned with the 12V header on the motherboard.
• The LED strip will only light up when the system is powered on.
• The LED strip is purchased separately.
12. RTC Battery connector (2-pin BATTERY)
This connector is for the lithium CMOS battery.
13. 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.
14. 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.
CLRTC
+3V_BAT GND
PIN 1
PIN 1
VBAT
GND
BATTERY
PIN 1
COM
DCD
TXD
GND
RTS
RI
RXD
DTR
DSR
CTS
Chapter 1: Product Introduction

1-5
15. 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].
16. 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.
17. M.2 slot (Key E)
This socket connects to an M.2 Wi-Fi device.
18. S/PDIF Out header
This header is for an additional Sony/Philips Digital Interface (S/PDIF) port.
Connect the S/PDIF Out module cable to this header, then install the module to
a slot opening at the back of the system chassis.
19. SPI TPM header
This header supports a Trusted Platform Module (TPM)
system with a Serial Peripheral Interface (SPI), allowing you
to securely store keys, digital certicates, passwords, and
data. A TPM system also helps enhance network security,
protects digital identities, and ensures platform integrity.
The SPI_TPM module is purchased separately.
20. System Panel header
This header supports several chassis-mounted functions.
• System power LED (4-pin PLED)
This 4-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.
AAFP
AGND NC SENSE1_RETUR SENSE2_RETUR
PORT1 L
PORT1 R PORT2 R
SENSE_SEND
PORT2 L
HD-audio-compliant
pin definition
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
SPDIF_OUT
+5V SPDIFOUT GND
TPM
PIN 1
VCCSPI
S_PLTRST#
F2_SPI_CS1#_R
+3V_SPI
F_SPI_CS0#_R
T_SPI_MISO
F_SPI_HOLD#_R
S_SPI_TPM_IRQ#
S_SPI_TPM_CS2#
F_BIOS_WP#_R
GND
T_SPI_CLK
T_SPI_MOSI
PRIME B660M-AJ D4

1-6
1.2.2 Rear panel connectors
677 8
31 2
9
4 5
ACT/LINK
LED
SPEED
LED
Ethernet port
Speed LED
Status Description
OFF 10Mbps connection
GREEN 100Mbps connection
ORANGE 1Gbps connection
Activity Link LED
Status Description
OFF No link
GREEN Linked
BLINKING Data activity
• System warning speaker (4-pin SPEAKER)
This 4-pin header is for the chassis-mounted system warning speaker. The speaker
allows you to hear system beeps and warnings.
• ATX power button/soft-off button (2-pin PWRSW)
This header is for the system power button. Pressing the power button turns the
system on or puts the system in sleep or soft-off mode depending on the operating
system settings. Pressing the power switch for more than four seconds while the
system is ON turns the system OFF.
• 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.
• Chassis intrusion header (2-pin CHASSIS)
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 connector when a chassis component
is removed or replaced. The signal is then generated as a chassis intrusion event.
1. DisplayPort. This port is for a DisplayPort-compatible device.
2. PS/2 Mouse/Keyboard combo port. This port connects to a PS/2 mouse or PS/2
keyboard.
3. 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
Chapter 1: Product Introduction

1-7
4. Line In port (light blue). This port connects the tape, CD, DVD player, or other audio
sources.
5. Line Out port (lime). This port connects a headphone or a speaker. In 4-channel,
5.1-channel, and 7.1-channel congurations, the function of this port becomes Front
Speaker Out.
6. HDMI®ports. These ports are for a High-Denition Multimedia Interface (HDMI®)
connector, and are HDCP compliant allowing playback of HD DVD, Blu-ray, and other
protected content.
7. USB 2.0 ports. These Universal Serial Bus (USB) ports are for USB 2.0 devices.
8. USB 3.2 Gen 2 (up to 10Gbps) ports. These Universal Serial Bus (USB) ports
connect to USB 3.2 Gen 2 devices.
9. Microphone port (pink). This port connects a microphone.
Refer to the audio conguration table 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 conguration
A chassis with an HD audio module in the front panel is required to support 7.1-channel
audio output.
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.
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1.3 Central Processing Unit (CPU)
This motherboard comes with a surface mount Intel®Socket LGA1700 for
12th Gen Intel®Core™, Pentium®Gold and Celeron®Processors.
Unplug all power cables before installing the CPU.
• Ensure that you install the correct CPU designed for LGA1700 socket only. DO NOT
install a CPU designed for LGA1155, LGA1156, LGA1151, and LGA1200 sockets on
the LGA1700 socket.
• ASUS will not cover damages resulting from incorrect CPU installation/removal,
incorrect CPU orientation/placement, or other damages resulting from negligence by
the user.
Installing the CPU
Take caution when lifting the load
lever, ensure to hold onto the load
lever when releasing the load
lever. Letting go of the load lever
immediately after releasing it may
cause the load lever to spring
back and cause damage to your
motherboard.
Chapter 1: Product Introduction

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PRIME B660M-AJ D4

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1.4 System memory
This motherboard comes with four Double Data Rate 4 (DDR4) Dual Inline Memory Module
(DIMM) sockets. The gure illustrates the location of the DDR4 DIMM sockets:
DIMM_B2
DIMM_B1
DIMM_A2
DIMM_A1
Channel Sockets
Channel A DIMM_A1 & DIMM_A2
Channel B DIMM_B1 & DIMM_B2
• 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.
• 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.
• Intel®12th Gen Processors support 3200/3000/2933/2800/2666/2400/2133 natively.
• 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.
• 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.
• Refer to www.asus.com for the Memory QVL (Qualied Vendors Lists), and data rate
support depends on the CPU types.
Recommended memory congurations
DIMM_B1
DIMM_B2
DIMM_A2
DIMM_B2
DIMM_A1
DIMM_A2
DIMM_A2
Chapter 1: Product Introduction