Hey Guepi and welcome to the build! Good eye on the BOM — and the short version is that everything you’re seeing is correct and intentional. The connector change all comes back to one thing: the Gamma Turbo runs on 12V, not 5V like the single-chip Bitaxe boards. Once you know that, your four questions mostly answer themselves.
1. Why an XT30 instead of a barrel jack?
Two reasons, both tied to the dual-chip design. First, the GT moved from a 5V input to a 12V input. Second, it pulls a lot more current — stock draw is around 43W, and the official supply for it is rated 12.4V / 10A (124W) to leave headroom. A small 5.5×2.1mm barrel jack is really only happy up to ~5A; push sustained higher current through one and you get heating, voltage drop, and eventually a loose, high-resistance (or arcing) connection. The XT30 comes from the RC/drone world, where it’s designed for exactly this: low resistance, a positive locking fit that won’t vibrate loose, and proper high-current handling.
The part itself (Amass XT30PW-M) is just the board-mount, male version of the XT30 — the “PW” is the PCB-mount body and the “-M” is male, so your power cable will end in a female XT30. Digikey doesn’t always stock the PCB-mount Amass variant, but it’s a totally standard part — any RC/hobby shop, Amazon, AliExpress, or an Amass distributor will have it. Just make sure you get the PCB-mount version (with the legs/pads), not the wire solder-cup version.
2. Is XT30 enough, or should I go XT60?
XT30 is plenty — no need to change. Even the most conservative rating for an XT30 is ~15A continuous (30A peak), and the better-tested figures are much higher with decent wire. At 12V, the official 124W supply is only ~10A, and even an aggressive overclock keeps you comfortably under the XT30’s rating. So you’re nowhere near its limit.
Also worth knowing: the PCB is laid out specifically for the XT30 footprint, so swapping to an XT60 isn’t a drop-in change anyway
3. Sealed brick vs. desktop ATX-style PSU?
For a single GT, a good sealed 12V brick is the cleaner choice: quiet, compact, nothing to configure, and it sits on the desk.
4. Can I reuse an old supply, like a 20-year-old 65W HP unit?
This is the one to be careful with — please check the label before connecting anything. Two problems with that HP brick:
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Voltage: old HP laptop adapters are almost always 18.5V or 19V, not 12V. The GT expects 12V. Feeding ~19V into a 12V board risks frying it. So unless the label literally says 12V DC, don’t use it, no matter how easy it’d be to fit an XT30.
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Wattage: even if it were 12V, 65W ≈ 5.4A at 12V. Stock draw is already ~43W, which leaves almost nothing for the overclocking you’re planning. The official supply is 124W for exactly that reason.
