ASUS Prime B450M-A II Motherboard: AM4, Ryzen 5000 and DDR4 explained

The ASUS Prime B450M-A II is a micro-ATX motherboard for AMD's AM4 processors. ASUS positions it as a solid foundation for a first build, with room to grow as your needs change. Here is what its specs mean and what to check before you build around it.

Socket and processor support

The AM4 socket supports Ryzen 5000 Series, plus 3rd, 2nd and 1st Generation Ryzen processors, according to ASUS. Older boards often need a firmware update before they can run newer chips, and ASUS flags that the BIOS must be up to date if you install a Ryzen 5000 Series CPU. You can find the latest BIOS on the support page for the model name, under Drivers and Tools. Because a board may ship with an older BIOS, check this before pairing it with a Ryzen 5000 processor.

Memory and storage

There are four DIMM slots supporting up to 128GB of DDR4 memory, with speeds up to 4400 MHz listed as overclocked (O.C.). Overclocked speeds depend on the memory kit and the processor, and aren't guaranteed. DDR4 is an older generation than DDR5, and the two are not interchangeable.

For storage, ASUS lists onboard M.2 support and NVMe. M.2 drives are small and connect directly to the board, with no cables. USB 3.2 Gen 2 offers 10Gbps transfer speeds for fast external drives.

Display outputs

The back panel provides HDMI 2.0b, DVI and D-Sub (VGA) outputs. These work only with processors that have integrated graphics. Many Ryzen chips lack them, in which case you will need a separate graphics card.

Cooling and fan control

ASUS lists a VRM and PCH heatsink with an extensive surface area, plus thermal pads that transfer heat from the inductors and power phases to the heatsink. The VRM is the circuitry that delivers stable power to the processor. Fan Xpert 2 plus is the ASUS software for fan controls, aimed at balancing cooling and quietness.

Protection and durability

ASUS says the board has:

• LANGuard
• DRAM overcurrent protection
• Overvoltage protection
• SafeSlot Core
• A stainless-steel back I/O panel
• Over 1000 compatible devices tested and more than 8000 validation hours

These are ASUS's claims about its testing and design.

Easy building and audio

BIOS Flashback lets you update the firmware from a USB drive without a processor installed, which is useful for older boards that need an update before a new CPU will boot. ASUS also describes a UEFI BIOS for tuning. For audio, ASUS mentions dedicated PCB layers, Japanese audio capacitors and shielding, which it says separates the analog and digital signals and reduces interference.

Lighting

Aura Sync RGB and the Armoury Crate utility synchronise lighting effects across compatible PC gear. The board has an RGB LED and an RGB header for customising.

Size

The board measures 9.6 x 9.5 x 2.0 inches and weighs 2.0 lb. Micro-ATX boards fit in micro-ATX and larger cases.

Who it suits

It suits someone building or upgrading a compact AM4 desktop who already has, or plans to source, DDR4 memory and an AM4 processor. If you want DDR5 or newer standards, you will need a newer platform.

What to check before you buy

• The exact processor, and whether it needs a BIOS update first.
• Whether it has integrated graphics, for the video outputs.
• DDR4 memory compatibility, and the memory qualified list on ASUS's site.
• Case size (micro-ATX) and the cooler's fit on the AM4 socket.
• Expansion and storage slot counts against your needs.
• Operating system. The listing mentions Windows 10 and Windows 7 64-bit.

The short version

• Micro-ATX AM4 board supporting Ryzen 5000 and earlier Ryzen processors; a BIOS update may be needed.
• Four DDR4 slots up to 128GB, with M.2 NVMe support and USB 3.2 Gen 2.
• HDMI, DVI and D-Sub outputs, BIOS Flashback, and a heatsinked VRM.
• Aura Sync RGB lighting and Armoury Crate software.

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