Bitaxe Gamma Turbo

You liked the idea of a Bitaxe Gamma but wanted more hashrate without leaving the open-source world. That is exactly what the Bitaxe Gamma Turbo is. It takes the same BM1370 chip the single-chip Gamma uses, puts two of them on one board, and gives you roughly double the terahash for the same lottery you were always playing. The catch, as ever, is that double a rounding error is still a rounding error, and the second chip brings a fussier power plug and more heat to manage.

The take

I run the single-chip Gamma and a Supra, not this one, so treat what follows as the family view rather than a bench test of my own GT. But the GT is close enough to those boards that the shape of it is familiar. It is the same open AxeOS firmware, the same BM1370 silicon, the same honest fact that you will not turn a profit at this hashrate. What changes is that there are now two chips instead of one, so you get around 2.2 to 2.4 TH/s where a Gamma gives you 1.2, and the board has grown up a bit to feed them. If you already understand what a Bitaxe is for, the GT is simply more of it. If you do not, start with a Gamma first, because the GT asks a little more of you before it earns its keep.

What the numbers actually mean

The headline is the dual BM1370 board. Two of the same chips that sit inside Bitmain’s industrial S21 Pro, on one open board in front of you. That is where the “double a Gamma” line comes from, and it is broadly true: a single-chip Gamma does about 1.2 TH/s, the GT does roughly 2.2 to 2.4. Be careful with the exact stock number, though. The open-source GT 801 board ships closer to 2.15 to 2.2 TH/s, and the 2.4-plus TH/s you see on the TinyChipHub listing is a lightly factory-tuned unit rather than a different chip. It is a gentle overclock they have done for you, not a lie, but read 2.4 as a tuned figure rather than a guaranteed floor.

Efficiency is the good news and it holds up. At stock the board sits around 18 to 20 J/TH, and a tuned unit gets you nearer the 16 J/TH the vendor quotes, which is right in line with the best small miners and the industrial gear it borrows silicon from. Power draw lands somewhere between 38 and 43W depending on how hard it is pushed, so it still costs a few quid a month to leave running. The one place the second chip shows up on your bill is heat: there is nearly twice as much of it to shed as on a plain Gamma, which is why the plug and the cooling matter more here than they did on the little board.

The plug nobody warns you about

If you have only ever run a single-chip Bitaxe you will reach for a USB-C charger, and it will not work. The GT wants 12V through an XT30 connector, the small yellow plug the RC crowd use, because two chips pull several amps and a phone charger simply cannot hold voltage under that kind of draw. The USB-C port is still there, but it is for flashing firmware and data, not power. Get this wrong, or use a loose or undersized supply, and you will see an XT30-style error while the hashrate wobbles and the errors climb, and it will look like a bad chip when it is really a bad plug. A 12V 5A to 10A brick is the sane default. It is not difficult, it is just a genuinely different power setup from the Gamma, and it is the single most common thing that trips people up on their first GT.

Where the overclock actually stops

The lesson from the single-chip Gamma carries straight over, only more so. The chips are not what runs out of headroom first. The voltage regulators on the back of the board are, and with two chips to feed there is more heat sitting on those little MOSFETs than on any single-chip board. Push the clock hard and the VRMs get hotter than the ASICs do, and they are there with no heatsink by default. So the people running the GT high are the people who have put copper heatsinks or 3D-printed cooling on the rear of the board and are keeping those regulators under about 80C, with the core under 70C. That is the real ceiling.

For a daily setting, one owner on r/BitAxe reported running 600 MHz at about 1175 mV, holding the core under 70C with hardware errors below one percent, which is the sort of sensible top end I would keep a board at if I wanted it to last. You will also see people posting 4.5 TH/s and the odd brush with 5, and those numbers are real, but they come with an AIO water cooler standing in for the stock fan and dedicated heatsinks on the regulators. Fun to watch, single-unit stuff, and well outside anything you would run all day. If you chase those figures you are cooling the board harder than you are mining with it.

One more thing worth knowing if you buy early into a board like this: the GT had a firmware wrinkle in its first months. The prototype boards were an 800 series, and when ESP-Miner added the official 801 board identifier in v2.11.0 it briefly broke hashrate for people still on the prototype 800 boards until a later beta sorted it. Not a reason to avoid the board now, but a reminder that open hardware in its first release sometimes asks you to keep up with the firmware.

Who should get one, and who shouldn’t

Get one if you already know what a Bitaxe is for and you want more of it. If you are happy sorting out a 12V supply, you do not mind adding a bit of VRM cooling to run it hard, and you like the idea of pointing double a Gamma’s hashrate at your own node, the GT is the natural step up. It sits above the entry-level single-chip Gamma 601 and competes with boards like the NerdQAxe++ for people who want more terahash from a small open miner.

Don’t get one as your first miner. The Gamma is cheaper, simpler, runs off a plug you already own, and teaches you the same lessons for less money and less fuss. And don’t get one expecting a return, because two chips of lottery odds is still lottery odds. The GT is for the person who has done the Gamma, understood it, and wants to turn the hashrate up without pretending the maths has changed.