Minisforum MS-A1, MS-A2, and MS-01: Which One Belongs in Your Rack

Minisforum has spent the last few years quietly building the machines that homelab people actually wanted: small boxes with real network interfaces, multiple NVMe slots, and enough PCIe to do something interesting. The MS line in particular has become a default recommendation for a virtualization host that does not sound like a jet and does not need a full-depth 19-inch chassis.

The result is that a lot of racks now contain an MS-something, and a fair number of people bought the wrong one for their cabinet. The MS-A1, MS-A2, MS-01, and MS-R1 are not interchangeable from a mounting perspective, and the differences are not the ones the spec sheets lead with. This is a look at all of them from the perspective of the person who has to get the box into a rack and keep it cool there.

The mount for this build:

19" Minisforum MS-01, MS-A2 & MS-R1 Rack Mount - 2U

The family, briefly

The MS-01 was the machine that made the line's reputation: a mobile Intel Core Ultra or 12th/13th-gen H-series part, dual SFP+ cages, dual 2.5GbE, three NVMe slots, and a half-height PCIe slot. It is a workstation-class part in a chassis about the size of a large paperback.

The MS-A1 traded the SFP+ cages for an AM5 socket, which is the interesting part — it takes desktop Ryzen, which means you choose your own thermal envelope and can put 8 or 12 cores in there if you want them. Networking drops to dual 2.5GbE.

The MS-A2 is the follow-on that put the SFP+ back, pairing a soldered Ryzen mobile part with dual 10G SFP+ and dual 2.5GbE. For a lot of people this is the sweet spot: the MS-01's networking with AMD's efficiency.

The MS-R1 is the ARM entry, built around a RISC-oriented platform with a different power profile entirely, and it shares enough of the chassis geometry with the MS-01 and MS-A2 that the same mounting hardware fits.

From a rack standpoint, the meaningful grouping is this: MS-01, MS-A2, and MS-R1 share a chassis footprint, and the MS-A1 does not. That is why the 19" Minisforum MS-01, MS-A2 & MS-R1 Rack Mount - 2U covers three models while the 19" Minisforum MS-A1 Rack Mount- 2U Height is its own part. If you buy on model name without checking which group you are in, you get a mount that is close but does not close.

Why these are all 2U

The recurring question is whether an MS-series box can be made to fit 1U. The answer is no, and the reason is worth understanding because it applies to a lot of mini PCs.

EIA-310-D defines one rack unit as 44.45 mm. That is the pitch, not the usable interior — real-world usable height inside a 1U opening lands closer to 43 mm once you account for the mount's own material thickness above and below the device. An MS-01 chassis is roughly 48 mm tall on its own. It does not matter how thin the mount is; the box is taller than the slot.

2U gives 88.9 mm of pitch, and after mount structure you have something in the 84 to 86 mm range of usable interior. An MS-series chassis at roughly 48 mm leaves 36 to 38 mm of clearance, which is where the design gets interesting — that gap is not wasted space, it is the thermal budget.

The MS-01 in particular pulls intake air from vents on the bottom and lower sides and exhausts out the rear. Mounting it flat against a solid tray blocks the bottom intake outright. A mount that holds the chassis with a standoff gap underneath, or one with a perforated tray, preserves the intake path. This is the single most common way people make an MS-01 run hot and then blame the CPU.

Thermals, honestly

The MS-01 with a 45 W-class mobile Intel part will boost well above its nominal TDP under sustained load, and the stock cooling is adequate but not generous. In free air on a desk, sustained all-core loads commonly settle in the 85 to 95 °C package range with the fan clearly audible. That is within spec and it is also not much margin.

Put the same machine in an enclosed 6U cabinet with the door shut and no ventilation and you will add somewhere between 5 and 12 °C to intake temperature, which comes straight off the top of your thermal headroom. Two consequences follow.

First, the fan curve gets aggressive, and an MS-01 at high fan speed in a closet is genuinely noticeable. Second, sustained clocks drop. If you bought the machine for a Proxmox host that runs compile jobs or transcodes, you are leaving performance on the table for want of an air path.

The MS-A1 with a desktop Ryzen part is the more interesting thermal case because you chose the TDP. A 65 W part in an MS-A1 behaves reasonably. A 105 W part in the same chassis in an enclosed rack is asking a lot of a cooler that lives in a 48 mm-tall box. If you are running the higher-wattage AM5 chips, set a PPT limit in the BIOS to something the chassis can actually dissipate — 65 W is a sane ceiling in a rack — and you will lose very little real-world throughput while gaining a machine that does not thermally oscillate.

Practical placement rules for any of these in a cabinet:

• Leave a vented rack unit below the machine if the mount does not provide a bottom air gap
• Do not stack an MS-series box directly above a NAS or a PoE switch, both of which are heat sources that vent upward
• Rear clearance matters — the exhaust needs somewhere to go that is not a sealed cabinet back panel 20 mm away
• If the cabinet has a door, it should be mesh or louvered, not glass

10-inch versus 19-inch

The MS chassis is roughly 196 mm wide, which is the number that decides this. A 10-inch mini rack has rails 254 mm apart, so a single MS-series box fits with a small margin on each side. That is exactly the geometry the 10" Minisforum MS-01, MS-A2 & MS-R1 Mini Rack Mount - 2U is built around, and it is a tidy solution for a desktop 6U or 8U mini cabinet.

Nineteen-inch rails at 482.6 mm give you enough width for two MS-series machines side by side in the same 2U, which is the configuration a lot of people end up wanting once they discover that one virtualization host means all the household infrastructure now depends on one machine. If a two-node cluster is even vaguely in your future, going 19-inch from the start saves you re-doing the mount.

The other 19-inch advantage is modularity. A modular mount lets you populate the remaining width with something else — a small switch, a set of keystones, a blank — rather than leaving 280 mm of dead air across the rack face.

The older Minisforum boxes, which are still good

Not everyone racking a Minisforum has an MS-series machine. The NAB and UM lines are common, cheap on the used market, and perfectly capable of running a Docker host or a Home Assistant instance.

The NAB6, NAB7, and NAB9 share a chassis and are a genuinely small box — the sort of machine that gets bought for a media PC, outgrows that role, and ends up in a rack. The Minisforum NAB6/NAB7/NAB9 10" Mini Rack Mount - 2U handles the mini-rack case. These machines run cool enough that the enclosed-cabinet penalty is much less of a concern than it is with an MS-01.

The UM690S is a slightly different shape and gets its own part, the Minisforum UM690S Mini PC Rack Mount 19" 2U (Modular). The UM line's Ryzen mobile parts are efficient and quiet, and a UM690S makes a much better always-on host in a closet than an MS-01 does if you do not need the SFP+ ports.

The SFP+ question is the real decision

Strip away the CPU comparisons and the choice between an MS-01 or MS-A2 on one hand and an MS-A1 or UM-series on the other comes down to whether you need 10G optics.

If your switch has SFP+ ports and you want a fast uplink to a NAS, the MS-01 and MS-A2 give you two of them directly on the board, and you avoid consuming the PCIe slot on a network card. That is a genuinely useful thing in a machine with exactly one half-height slot.

If your network is 2.5GbE end to end — which for most homelabs it is, and honestly is plenty — the SFP+ cages are two ports you will never populate, and the MS-A1's socketed AM5 gives you a machine you can put a better CPU into in three years. That is a real form of longevity in a category where most devices are e-waste at end of life.

One practical note on SFP+ modules: they run hot. A pair of 10GBASE-T copper SFP+ modules can add 4 to 6 W of dissipation each right at the back of a chassis that was not designed with that in mind. In a rack, prefer fiber or DAC over copper SFP+ if you have the choice, purely on thermal grounds.

A build that works

For anyone assembling this from scratch, a configuration that has held up well in practice:

• Machine: MS-A2 if you need 10G, MS-A1 with a 65 W-limited Ryzen if you do not
• Position: middle of the rack, never the top slot in an enclosed cabinet
• Below it: a vented rack unit, giving the bottom intake clean air
• Above it: anything passive — patch panel, blank, a small hub
• Storage: populate all NVMe slots at build time, because getting back into the chassis means unracking it
• Power limit: set it in BIOS before you rack the machine, not after you notice the fan

The last point deserves emphasis. Everything that requires opening the chassis should happen on a workbench before the machine goes in the rack. RAM, all storage, the PCIe card, BIOS settings, and a burn-in run under sustained load with a thermometer. An MS-series box in a rack is a fifteen-minute job to remove and reinstall, and you will not want to do it twice.

Wrap-up

The MS-01, MS-A2, and MS-R1 share a footprint and share a mount; the MS-A1 does not, and that is the first thing to check before ordering hardware. All of them are 2U devices because the chassis is roughly 48 mm tall against a 44.45 mm rack unit, and no amount of clever mount design changes that arithmetic.

Beyond fitment, the decision is mostly about whether you need SFP+ on board and whether you want a socket you can upgrade. Get the thermal path right — bottom intake unobstructed, a vented unit below, nothing hot underneath — and any of these machines will run quietly in a closet for years.

Mounts in this build