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MSI MAG B550M MORTAR WIFI Upgrade Guide: RAM, Storage and CPU

Mis à jour le 31 octobre 2026 · Rédigé d'après les spécifications vérifiées de cet appareil

The MSI MAG B550M MORTAR WIFI is a micro-ATX motherboard with socketed memory, storage and processor, so all three are worth upgrading. This guide covers what fits, the limits to watch for, and how to fit a new part safely. The plain MORTAR (non-WiFi) version is the same board minus the Wi-Fi/Bluetooth module, so everything here applies to both.

En bref

  • RAM: 4 DDR4 DIMM slots, up to 128 GB total, up to 4400 MT/s with A-XMP overclocking.
  • Storage: 2 M.2 slots (2242/2260/2280) plus 6 SATA 6Gb/s ports.
  • CPU: socket AM4, Ryzen 3000 and Ryzen 5000 desktop chips plus Ryzen 4000G APUs; up to Ryzen 9 class (105 W).
  • Watch out: a drive in the second M.2 slot disables the bottom PCIe x16 slot, and older boards may need a BIOS update before a Ryzen 5000 CPU will start.
4x DDR4 DIMM (288 broches), max. 128 GB4 × DDR4 DIMM · jusqu'à 128 GB au total · 4400 MT/s
2x M.2 Key M (2242/2260/2280) + 6x SATA 6Gb/s8 × SSD M.2 2242 / M.2 2260 / M.2 2280 (NVMe / SATA)
1x socket AM4 (PGA, remplaçable)AM4 · Ryzen 3000, Ryzen 5000 · max 105 W
CPU · AM4max 105 W4 × DIMM · DDR4jusqu'à 128 GB au total2x M.2 Key M (2242/2260/2280) +6x SATA 6Gb/s8 × SSD M.2 2242 / M.2 2260 /M.2 2280 (NVMe / SATA)
Schéma des slots extensibles (pas à l'échelle). Vérifiez le manuel de l'utilisateur pour leur position exacte.

Cycle de vie et support

Un modèle actuel : vendu neuf et supporté.

20202021202220232024202520262027Aujourd’hui11 · Commercialisation · 30 juin 2020
Points pleins : dates publiées par le fabricant. Points creux : estimations de sources tierces.
JalonDate
Commercialisation
Premier jour de vente.
30 juin 2020 Estimation First availability of the WIFI variant per kakaku.com 発売 2020年6月30日; mindfactory.de shows it in catalogue since 2020-06-19 (regional street date). No MSI launch date published.
Source ↗

Les dates non listées n'ont pas été publiées par le fabricant ou une source tierce fiable.

Memory (RAM)

You have four 288-pin DDR4 DIMM slots, dual-channel, with nothing soldered on the board. The maximum is 128 GB in total; the practical ceiling per module is 32 GB, since 4 x 32 GB is the validated maximum (64 GB modules are not validated). This board takes DDR4 only - DDR5 will not fit and is not compatible either way. Registered memory (RDIMM/LRDIMM) is not supported; you want standard unbuffered desktop DIMMs. ECC UDIMMs physically fit but run in non-ECC mode, so don't buy them hoping for error correction.

Conseils d'achat

  • Buy matched kits - for example one kit of 2 or 4 modules - rather than two separate packages. Kingston warns against mixing kits or mismatching speed, timings and voltage.
  • Install modules in pairs to get dual-channel mode.
  • Don't chase the headline 4400 MT/s: that figure is with A-XMP overclocking and one single-rank module per channel. Kingston notes Ryzen 3000/5000 systems are happiest around DDR4-3600 with the memory clock in 1:1 mode, and faster kits clock down depending on your CPU and how many modules you fit.

Storage (SSD / hard drive)

There are eight storage connections: two M.2 Key M slots and six SATA 6Gb/s ports. Both M.2 slots take 2242, 2260 or 2280 drives. The board itself has no 2.5-inch or 3.5-inch bays - how many drives you can mount physically depends on your case.

Conseils d'achat

  • M2_1 is fed directly by the CPU and accepts NVMe or SATA M.2 drives. It runs PCIe 4.0 only with a Ryzen 3000 or Ryzen 5000 processor; with any other supported CPU it runs at PCIe 3.0 speeds.
  • M2_2 is NVMe-only at PCIe 3.0 x4 - a SATA M.2 drive bought for this slot will not work. Filling it also disables PCI_E4, the bottom PCIe 3.0 x16 (x4) slot, so plan add-in cards around that.
  • The 2230 Key-E slot is for the Wi-Fi module, not storage - you can't put an SSD in it.
  • The board supports RAID 0/1/10 on SATA and RAID 0/1 on M.2 NVMe drives.

Processor (CPU)

The processor sits in a socketed AM4 socket and is fully replaceable. MSI's current support list covers AMD Ryzen 5000 and Ryzen 3000 desktop processors plus Ryzen 4000 G-Series APUs. Two older APUs are explicitly not compatible: the Ryzen 5 3400G and Ryzen 3 3200G. Ryzen 5000 G-Series APUs such as the 5600G and 5700G are not on MSI's list even though they use AM4, so check MSI's CPU support page before buying one - it may or may not work.

Conseils d'achat

  • MSI does not publish a numeric TDP limit, but the board supports up to Ryzen 9 class processors - 105 W chips - backed by the 8-pin CPU power connector. Overclocking draws more, so your cooler and airflow are the practical limits.
  • MSI's regional pages still use older wording ('3rd Gen Ryzen, and future Ryzen with BIOS update') while the US page lists Ryzen 5000/3000/4000G. The US list is the more current one, but the CPU support page is the final word.
  • Boards from older stock may need a BIOS update before a Ryzen 5000 CPU will POST. If you don't have an older AM4 chip to borrow for the update, buy from a seller advertising 'Ryzen 5000 ready' or ask the seller to confirm the BIOS version.

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Comment mettre à niveau

Avant de commencer

  • Back up anything important first.
  • Shut down, switch off at the PSU and unplug the power cable.
  • Ground yourself to discharge static before touching components.
  • Open the case following the owner's manual - disassembly varies by case, and the manual is the reference for exact mounting points and screws.
  • Install the new part as shown in the manual, then close the case.
  • Start the PC and check that the BIOS/firmware sees the new memory, drive or processor, and that the installed capacity and drive are listed correctly.

Étapes

  1. RAM installation notes
    Fit modules in pairs for dual-channel performance, using matched modules from one kit. After the first boot, confirm the total capacity and speed in the BIOS; if you want the faster profile, enable A-XMP there - but remember the board supports up to 4400 MT/s only as an overclocked setting, and speeds fall when the slots are heavily populated or the modules are dual-rank.
  2. SSD installation notes
    Decide which M.2 slot you want before buying: only the first slot (M2_1) accepts a SATA M.2 drive, and only the first slot runs PCIe 4.0, and only with a Ryzen 3000/5000 CPU. Keep in mind that a drive in M2_2 turns off the bottom PCIe x16 slot. When the drive is fitted and the PC is closed up again, check in the BIOS that the drive is detected before installing your operating system on it.
  3. CPU installation notes
    Before the swap, check the board's BIOS version against MSI's CPU support list. Older boards may need a BIOS update to run a Ryzen 5000 chip, and getting that update done beforehand can save you a boot failure - some setups need an older AM4 processor in place to perform the update. After installation, open the BIOS and confirm the processor model is recognised.

Bon à savoir

  • The 32 GB per-module ceiling is inferred from the 128 GB maximum across four slots and confirmed by Kingston's 4 x 32 GB kits; no source states a per-module limit outright.

Foire aux questions

How much RAM can the MSI MAG B550M MORTAR WIFI take?

128 GB in total across its four DDR4 DIMM slots, using 32 GB modules. 64 GB modules are not validated for this board.

Does it support DDR5?

No. The board is DDR4-only, with four 288-pin desktop DIMM slots. DDR5 is a different shape and generation and will not fit.

Does it support ECC memory?

ECC UDIMMs physically fit but run in non-ECC mode, so you get no error correction. Registered server memory (RDIMM/LRDIMM) is not supported at all.

Can I use two M.2 SSDs and a PCIe card at the same time?

You can use both M.2 slots at once, but a drive in the second slot (M2_2) disables PCI_E4, the bottom PCIe 3.0 x16 (x4) slot. Plan your expansion cards around that trade-off.

Which CPUs fit the MSI MAG B550M MORTAR WIFI?

AM4 chips on MSI's list: Ryzen 5000 and Ryzen 3000 desktop processors and Ryzen 4000G APUs, up to Ryzen 9 class. The Ryzen 5 3400G and Ryzen 3 3200G are explicitly not compatible, and Ryzen 5000 G-Series APUs are not on MSI's list - check the CPU support page before buying an APU.

Do I need a BIOS update for a Ryzen 5000 CPU?

Possibly. Boards from older stock may not start with a Ryzen 5000 processor until the BIOS is updated, and the update may require an older AM4 chip. Check the BIOS version with your seller before buying, or look for a board advertised as Ryzen 5000 ready.

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