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MSI MAG B550M Mortar review

Proving that a decent Socket AM4 motherboard for AMD Ryzen CPUs doesn't need to cost over $200, this micro-ATX B550 motherboard from MSI nails its brief.

MSI MAG B550M Mortar

Our Verdict


MSI does B550 the way it should be, with a sub-$200 board that can handle a top-end CPU and a PCIe 4 SSD.

Thankfully, you don’t need to spend over $200 to bag an AMD B550 motherboard, and the MSI MAG B550M Mortar strikes the right balance between features and price. You get PCIe 4 support, of course, but MSI hasn’t devastated other features, or the board’s cooling. It also includes MSI’s BIOS Flashback feature, so if you pick up the board in six months to pair with a Zen 3 CPU, you’ll be able to update the BIOS to a compatible version without needing an old CPU.

At Custom PC, we’ve been reviewing and overclocking the latest motherboards since we first launched in 2003, so we know exactly what to look for in terms of layout, features, performance, and overclocking abilities.

The MSI Mag B550M Mortar also comes with an M.2 heatsink for the PCIe 4 M.2 slot, but you can use PCIe 3 and SATA SSDs in this slot as well, plus there’s a second slot that’s limited to PCIe 3 SSDs. You get one more fan header than the more expensive Asus TUF B550M-Plus Gaming, which also lacks the MAG B550M Mortar’s integrated I/O shield and M.2 heatsink, as well as its USB 3.1 Type-C header for compatible cases, even if it’s limited to USB 3 speeds.

The MSI board also has two more SATA 6Gbps ports than the Asus, and four of them are even right-angled. In addition, the MSI sports larger VRM heatsinks than the Asus, for its eight CPU power phases, although it does lack the Asus board’s Wi-Fi and plentiful USB ports.

While the MAG B550M Mortar kept our M.2 SSD below 60°C under load, which was over 10°C cooler than without it, it wasn’t quite as effective as the larger heatsinks available on some B550 boards. That said, the VRM peak temperature of 54°C is excellent and well away from any throttling.

It’s good to see Realtek ALC1200 audio at this price too, plus a smattering of 3-pin and 4-pin RGB headers and 2.5 Gigabit Ethernet. However, the thermal probe input and Corsair RGB lighting connector of the ATX MSI MPG B550 Gaming Carbon WiFi are absent, as are all other overclocking and testing tools.

The MAG B550M Mortar showed little sign of being slower or less capable than boards costing twice as much in our benchmarks. You clearly don’t lose out on speed by opting for this cheaper board.

When it came to overclocking, the Mortar needed more voltage to overclock our Ryzen 9 3900X than the Gigabyte B550 Aorus Master, but it still easily pushed the CPU to its 4.3GHz limit with the usual 1.4125V vcore applied. If you want a cheap way to jump on the PCIe 4 SSD bandwagon, then the SSD read and write speeds of 4,990MB/s and 4,274MB/s respectively prove that’s possible here too.

MSI MAG B550M Mortar pros and cons


  • PCIe 4 for under $170
  • Good VRM cooling
  • Decent features for the price


  • No Wi-Fi
  • USB-C header only runs at USB 3 speed
  • Only five I/O panel USB ports

MSI MAG B550M Mortar specs

The MSI MAG B550M Mortar specs list is:

Chipset AMD B550
CPU socket AMD Socket AM4
Memory support 4 slots: max 128GB DDR4 (up to 4400MHz)
Expansion slots One 16x PCIe 4, one 16x PCIe 3, 1x PCIe 3
Sound 8-channel Realtek ALC1200
Networking Intel 2.5 Gigabit LAN
Cooling Five 4-pin fan headers, VRM heatsinks
Ports 6 x SATA 6Gbps 1 x M.2 PCIe 4, 1 x M.2 PCIe 3, 3 x USB 3, 1 x USB 3 Type-C, 2 x USB 2, 1 x LAN, 3 x surround audio out
Dimensions (mm) 244 x 244

MSI MAG B550M Mortar price

Price: Expect to pay $169 (£157).

MSI MAG B550M Mortar review conclusion

You don’t get loads of features with the MSI MAG B550M Mortar, with obvious omissions being Wi-Fi and USB 3.1 (Gen 2) support, and there are no frills when it comes to overclocking and testing tools.

However, MSI has made sensible trims to the specs to keep the price low, while still offering a motherboard that can handle AMD’s most powerful Ryzen CPUs and support PCIe 4 SSDs. If you don’t mind dropping to the micro-ATX form factor, and you’re looking for a budget route to PCIe 4, this is the B550 board to get.

Since we first published this review in 2020, AMD has released its Zen 4 architecture. If you want to upgrade to one of the latest AMD CPUs, such as the Ryzen 7 7800X3D, then make sure you also check out our full guide to the best AMD AM5 motherboard, which runs through several options at a range of prices.