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Green rectangular micro-ATX board with silver heatsinks and black slots

ASUS

ASUS Prime B450M-A II AMD AM4 AMD motherboard

SKU CH-VTNA-1WTJK

Micro-ATX board for AM4 Ryzen CPUs with four DDR4 slots up to 128 GB, PCIe 3.0 x16, M.2, USB 3.2 Gen 2 and HDMI 2.0b

  • CPU Socket TypeAM4
  • CPU TypeAMD AM4 Socket for 3rd/2nd/1st Gen AMD Ryzen / 2nd and 1st G
  • ChipsetAMD B450
  • Number of Memory Slots4x288pin (DDR4)
  • Memory StandardDDR4 4400(O.C.)/ 4000(O.C.)/ 3866(O.C.)/ 3733(O.C.)/ 3600(O.
  • Maximum Memory Supported128GB
  • Supports Ryzen 5000 and earlier AM4 processors
  • USB 3.2 Gen 2 delivers 10Gbps transfer speed
  • Four DDR4 slots accept up to 128GB at 4400 O.C.
  • VRM and PCH heatsinks with thermal pads improve cooling
  • LANGuard, DRAM overcurrent and overvoltage protection increase durability

AM4 Socket and Ryzen Support

The ASUS Prime B450M-A II uses the AMD B450 chipset and an AM4 socket that accepts Ryzen 5000 series and 3rd, 2nd, and 1st Gen Ryzen processors. Four DDR4 slots support up to 128 GB of memory with overclocked speeds reaching 4400 MHz. The board targets builders who want a compact micro-ATX foundation for productivity or general computing.

Connectivity and Build Features

A single M.2 socket takes 2242, 2260, 2280, and 22110 drives in both SATA and PCIe 3.0 x4 modes, while six SATA 6 Gb/s ports handle additional storage. Video output relies on the processor and provides HDMI 2.0b, DVI-D, and D-Sub ports. Rear USB includes 3.2 Gen 2 at 10 Gbps. VRM and PCH heatsinks with thermal pads manage heat, and stainless-steel back I/O plus LANGuard and SafeSlot Core protections reinforce durability.

PCIe 3.0 and 1 Gbps LAN Limits

The primary PCIe 3.0 x16 slot runs at x16 with 3rd Gen Ryzen and drops to x8 with 2nd and 1st Gen Ryzen, while Athlon CPUs limit it further. Two PCIe 2.0 x1 slots handle add-in cards. Networking is handled by a Realtek RTL8111H controller capped at 1 Gbps. Memory overclocks above 2666 MHz are not guaranteed and depend on the specific CPU and DIMM combination.

Highlights

  • Supports Ryzen 5000 and earlier AM4 processors
  • USB 3.2 Gen 2 delivers 10Gbps transfer speed
  • Four DDR4 slots accept up to 128GB at 4400 O.C.
  • VRM and PCH heatsinks with thermal pads improve cooling
  • LANGuard, DRAM overcurrent and overvoltage protection increase durability

Specifications

BrandASUS
ModelPrime B450M-A II
CPU Socket TypeAM4
CPU TypeAMD AM4 Socket for 3rd/2nd/1st Gen AMD Ryzen / 2nd and 1st Gen AMD Ryzen with Radeon Vega Graphics / Athlon with Radeon Vega Graphics Processors *
* Refer to www.asus.com for CPU support list
ChipsetAMD B450
Number of Memory Slots4x288pin (DDR4)
Memory StandardDDR4 4400(O.C.)/ 4000(O.C.)/ 3866(O.C.)/ 3733(O.C.)/ 3600(O.C.)/ 3466(O.C.)/ 3400(O.C.)/ 3300(O.C.)/ 3200(O.C.)/ 3000(O.C.)/ 2800(O.C.)/ 2666/ 2400/ 2133 MHz Un-buffered Memory *
ECC Memory (ECC mode) support varies by CPU.
* Refer to www.asus.com for the Memory QVL (Qualified Vendors Lists).
* The maximum memory frequency supported varies by processor.
Maximum Memory Supported128GB
Channel SupportedDual Channel
PCI Express 3.0 x163rd/2nd/1st Gen AMD Ryzen Processors
1 x PCIe 3.0 x16 (x16 mode)
2nd and 1st Gen AMD Ryzen with Radeon Vega Graphics Processors
1 x PCIe 3.0 x16 (x8 mode)
AMD Athlon with Radeon Vega Graphics Processors
1 x PCIe 3.0 x16 (x4 mode)
PCI Express x16None
PCI Express x12 x PCI Express 2.0 x1 slots
Serial ATA (SATA)6 x SATA 6Gb/s
M.23rd/2nd/1st Gen AMD Ryzen / 2nd and 1st Gen AMD Ryzen with Radeon Vega Graphics: *
1 x M.2 Socket 3, with M key, type 2242/2260/2280/22110 storage devices support (SATA & PCIE 3.0 x4 mode)
Athlon with Radeon Vega Graphics Processors: *
1 x M.2 Socket 3, with M key, type 2242/2260/2280/22110 storage devices support (SATA mode)
* The M.2 slot shares bandwidth with the SATA6G_5/6 ports, and therefore the SATA6G_5/6 ports cannot be used when an M.2 device is installed.
SATA RAID0/1/10
Onboard Video ChipsetIntegrated Graphics in the 2nd and 1st Gen AMD Ryzen with Radeon Vega Graphics / Athlon with Radeon Vega Graphics Processors *
1 x D-Sub
1 x DVI-D
1 x HDMI 2.0b
* Graphics specifications may vary between CPU types.
Audio ChipsetRealtek High Definition Audio CODEC
Audio Channels7.1 Channels
LAN ChipsetRealtek RTL8111H
Max LAN Speed1Gbps
Back I/O Ports1 x PS/2 keyboard/mouse combo port(s)
1 x DVI-D
1 x D-Sub
1 x HDMI
1 x LAN (RJ45) port(s)
2 x USB 3.2 Gen 2 (teal blue) (2 x Type-A)
4 x USB 3.2 Gen 1 (blue) Type-A
3 x Audio jack(s)
1 x BIOS FlashBack Button(s)
HDMI1 x HDMI
USB 3.03 x USB 3.0
Onboard USB1 x USB 3.2 Gen 1 (up to 5Gbps) connector(s) support(s) additional 2 USB 3.2 Gen 1 port(s) (19-pin)
2 x USB 2.0 connector(s) support(s) additional 4 USB 2.0 port(s)
Other Connectors1 x CPU Fan connector(s) (1 x 4-pin)
2 x Chassis Fan connector(s) (2 x 4-pin)
1 x SPI TPM header
1 x COM port(s) connector(s)
1 x S/PDIF out header(s)
1 x Front panel audio connector(s) (AAFP)
1 x System panel(s)
1 x Clear CMOS jumper(s)
1 x COM port header
1 x Speaker connector
1 x RGB Header
Form FactorMicro ATX
LED LightingRGB
Dimensions (W x L)9.6" x 9.5"
Power Pin1 x 24-pin EATX Power connector(s)
1 x 8-pin ATX 12V Power connector(s)
Windows 11Supported
FeaturesSoftware Features:
ASUS Exclusive Software
Armoury Crate
- AURA Creator
- AURA Sync
AI Suite 3
- Performance and Power Saving Utility
TurboV EVO
EPU
DIGI+ VRM
Fan Xpert 2+
PC Cleaner
- EZ update
- System Information
ASUS CPU-Z
AI Charger
ASUS EZ Installer
DAEMON Tools
Norton Anti-virus software (Free Trial for 60 days)
WinRAR
UEFI BIOS
ASUS EZ DIY
- ASUS CrashFree BIOS 3
- ASUS EZ Flash 3
- ASUS UEFI BIOS EZ Mode
ASUS Special Features:
ASUS 5X PROTECTION III
- ASUS DIGI+ VRM
- ASUS LANGuard
- ASUS Overvoltage Protection
- ASUS SafeSlot Core
- ASUS Stainless-Steel Back I/O
ASUS Q-Desi
Package ContentsAccessories:
User's manual
I/O Shield
2 x SATA 6Gb/s cable(s)
1 x M.2 Screw Package
1 x Supporting DVD

Questions about this item

What PCIe generation and lane width does the single M.2 socket on this Prime B450M-A II actually deliver?

The M.2 Socket 3 with M key runs at PCIe 3.0 x4 and accepts 2242, 2260, 2280 and 22110 modules.

What board size and mounting pattern does this micro-ATX motherboard use?

It follows the micro-ATX form factor with the standard four mounting holes for that size.

How do you update the BIOS on this board without a supported CPU installed?

Use the BIOS Flashback button on the rear I/O: copy the renamed BIOS file to a FAT32 USB stick, plug it into the dedicated port, press the button and wait for the LED to finish blinking.

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