ASRock B450M Steel Legend Upgrade Guide

Lifecycle and support

A current model: sold new and supported.

Dates not listed haven't been published by the manufacturer or a reliable third party.

Memory (RAM)

There are 4 full-size 288-pin DDR4 DIMM slots (not laptop SO-DIMMs), running in dual channel. Nothing is soldered, so you can replace or add modules freely.

What fits: un-buffered DDR4 UDIMMs, either ECC or non-ECC. Registered or buffered server memory does not fit and is unsupported. DDR, DDR2 and DDR3 modules physically do not fit and can damage the board if forced.

Capacity: ASRock's current product page says up to 128 GB using four 32 GB DIMMs, while the printed manual and Kingston both say 64 GB. The disagreement looks like a spec revision — ASRock later validated 32 GB modules. Our advice: 4 x 16 GB (64 GB) is the universally safe configuration; 128 GB needs 32 GB modules plus a recent BIOS and may not run at top speed.

Speed: up to 3533 MT/s (overclocked) is listed with Pinnacle Ridge CPUs; the ceiling varies by processor family and is lower on some. Expect the board to downclock when you fill all four slots, especially with dual-rank modules. Actual speed depends on your CPU's memory controller and how many modules you install.

How to install: dual channel needs matched pairs, and ASRock recommends filling slots A2 and B2 first (the second and fourth slots from the CPU). One or three sticks will not run in dual channel. If you are running an APU, ECC memory is only supported with PRO CPUs; otherwise ECC support on this platform is best treated as 'module accepted' rather than a full workstation feature.

Buying tip: buy a matched kit of two or four identical DDR4 modules rather than mixing sticks, and prefer 3200 MT/s modules unless you enjoy tuning — they are the sweet spot across supported CPUs.

Buying tips

• Matched DDR4 UDIMM kits only — no registered/buffered memory
• Fill A2 and B2 first for dual channel
• 64 GB (4x16) is the safe target; 128 GB needs 32 GB modules and a recent BIOS
• Expect lower speeds with all four slots populated

Storage (SSD and hard drives)

The board gives you six storage connections: 4x SATA3 6 Gb/s ports and 2x M.2 sockets.

M2_1 (the top socket, labeled Ultra M.2) is the fast one: NVMe PCIe Gen3 x4 (about 32 Gb/s) with most supported CPUs, dropping to Gen3 x2 with Athlon APUs. It physically takes 2242, 2260 and 2280 drives. NVMe boot is supported, and ASRock offers a U.2 kit if you want to connect a U.2 drive via adapter.

M2_2 is the one buyers get wrong: it is SATA-only. An NVMe drive will not work in it. It takes 2230/2242/2260/2280 drives (the manual's wording about 2230 support varies between revisions). Note also that M2_2 shares lanes with SATA port 3 — use one and the other is disabled.

Limits to know: this is a B450 board, so there is no PCIe Gen4 — even a Gen4 SSD will run at Gen3 speeds here. Maximum drive capacity is not officially stated, but modern multi-terabyte SATA and NVMe drives work. The board imposes no drive bay or thickness limits; those come from your case, which must also be micro-ATX (24.4 x 24.4 cm).

Buying tip: put your main NVMe SSD in M2_1. Use M2_2 only for a SATA M.2 drive, and remember you give up one SATA port for it. The sample drive list in the manual is a validation list, not a restriction — any compatible drive of the right type and length should work.

Buying tips

• NVMe drives go in M2_1 only; M2_2 is SATA-only
• Check drive length: 2242/2260/2280 on M2_1
• Using M2_2 disables SATA port 3
• No Gen4 — drives run at Gen3 x4 at best

Processor (CPU)

The CPU sits in a socketed AM4 socket (PGA) — it is replaceable, not soldered. ASRock's current support list covers Ryzen 2000, 3000, 4000 G-Series, 5000 and 5000 G-Series desktop processors plus Athlon models. The older manual only lists support up to Ryzen 3000, so treat the current product page as the up-to-date reference. Ryzen 1000 appears only in that older documentation, so support there is uncertain.

The big caveat is BIOS: Ryzen 4000G, 5000 and 5000G need a newer BIOS (AGESA 1.2.0.x or later). If you buy old-stock, the board may need a supported older CPU installed just to flash the update first, unless the box carries a 'Ryzen 5000 Ready' sticker. Check this before buying a new processor.

Power: ASRock does not publish a maximum TDP. The board uses a 6-phase VRM design, and 105 W parts (such as the Ryzen 9 3950X and 5950X) do appear on the support list. Treat 105 W as the practical ceiling, and expect the VRM to run warm on 12- and 16-core chips — good case airflow matters. Always verify your exact CPU model on ASRock's support list for this board before ordering.

Buying tip: if the board is already running, update the BIOS to the latest version before swapping CPUs — that removes most of the compatibility risk in one step.

Buying tips

• Check ASRock's support list for your exact CPU model
• Update the BIOS before the swap if the current CPU still works
• Look for 'Ryzen 5000 Ready' if buying a board for a Ryzen 5000 chip
• 105 W is the practical VRM ceiling; cooling matters on big chips

How to upgrade

Before you start

• Back up anything important before opening the case.
• Shut down, switch off the PSU and unplug the power cable.
• Ground yourself to avoid static damage — touch the bare case or use a strap.
• Open the case and install the part. For RAM, note that the release latches on the DIMM slots close when a module is seated; for M.2 drives, match the screw/standoff position to the drive length. For the exact layout and disassembly, follow the owner's manual.
• Close the case, reconnect power and boot into the BIOS to confirm it detects the new RAM, drive or CPU — and that the memory is running at the expected speed.

Steps

1. General installation outline
   1. Back up your data first. 2. Power down, switch the PSU off and unplug the mains cable. 3. Ground yourself before touching components. 4. Open the case and fit the new part — see the manual for exact slot positions and screws. 5. Close up, reconnect power and boot. 6. Enter the BIOS and confirm the new part is detected and running correctly. For a CPU upgrade to a Ryzen 4000G/5000 series chip, the BIOS update should already be done beforehand.

Good to know

• The B450M Steel Legend is not the ATX B450 Steel Legend — different SATA and M.2 counts.
• RAM maximum is quoted differently in different ASRock documents (64 GB vs 128 GB).
• Ryzen 4000G/5000/5000G support depends on the BIOS version being up to date.

Frequently asked questions

How much RAM can the ASRock B450M Steel Legend take?

ASRock's current page says 128 GB with four 32 GB modules, but the manual and Kingston both say 64 GB. In practice, 64 GB (4 x 16 GB) is the safe bet; 128 GB needs 32 GB modules, a recent BIOS and no promise of top speed.

Does the B450M Steel Legend support NVMe?

Yes — the top M.2 socket (M2_1) supports NVMe drives at PCIe Gen3 x4 with most supported CPUs, and NVMe booting works. The second M.2 socket is SATA-only, and NVMe speeds top out at Gen3 because B450 has no PCIe Gen4.

Does it support Ryzen 5000?

Yes, per ASRock's current support list, along with Ryzen 2000, 3000, 4000G and 5000G. However, Ryzen 4000G/5000/5000G require a BIOS update first. Old-stock boards may need an older supported CPU to flash that update unless the box has a 'Ryzen 5000 Ready' sticker.

Can I use ECC memory?

ECC and non-ECC un-buffered modules are both listed as supported, but on APU models ECC works only with PRO CPUs. Registered/buffered server memory is not supported at all. Don't buy this board expecting full workstation-grade ECC error reporting.

What's the difference between the B450M Steel Legend and the B450 Steel Legend?

The B450M Steel Legend is the micro-ATX board with 4 SATA ports and 2 M.2 sockets. The ATX B450 Steel Legend is a different board that adds two extra SATA ports and another M.2 socket. Check the model name before buying parts.

Does it support PCIe Gen4 SSDs or graphics?

No. This is a B450 chipset board and there is no PCIe Gen4 support. Gen4 drives will work but run at Gen3 speeds (Gen3 x4 maximum in the NVMe M.2 slot).

Official documents and references

• PDF ASRock B450M Steel Legend user manual (PDF)
  Official manual: slot layouts, memory population order, per-CPU memory speed tables, M.2 and SATA details.
• ASRock B450M Steel Legend product page
  Current specifications and CPU/memory support — the most up-to-date reference on capacity and supported processors.
• Kingston memory configurator for the B450M Steel Legend
  Compatibility reference for DDR4 modules and supported configurations.