GMKtec K12

What owners say

Four labs had this H 255 box — a chip one of them calls a rebadged 7840HS — and they heard three different machines. Notebookcheck found it loud even at idle, 35 dB(A) in a 24 dB(A) room; TechStage never saw more than 36 dB(A) at full load and mostly 28 to 32 without it; TechRadar called it silent in office use. The same spread shows in heat: settling at 78 °C in one stress test, an 83 °C peak falling to 60 °C over half an hour in another, never above 70 °C in a third that ran it at 65 W. It is larger and heavier than the K11, and the extra room buys three M.2 slots, one x4 and two x2. Idle draw is 11 to 13 W, load averages about 70 W, and the rear USB4 port can also power the machine. One review unit arrived with a loose screw on the board, and the fan cable is short enough to come unplugged when opening it. The case button changes the fan's colour, not its speed. Proxmox owners got graphics passthrough working, but one saw memory errors with mismatched sticks until he fitted a matched pair of 48 GB modules, and another reports unexplained crashes under Windows.

For whom

A roomy, well-connected mini PC for office work, development or a Proxmox host that needs three SSDs.

Not for

Anyone who needs it small or reliably silent at idle, and recent heavy games, which need low settings.

Our own summary of 5 published sources, reviewed Sep 23, 2026. We have not tested this Mini PC ourselves; the sources are listed under About this data.