Bitaxe Supra

Before the Gamma, the Supra was the Bitaxe to buy. It’s the BM1368 board: a single real ASIC chip on an open-source card, hashing at about 0.7 TH/s for the cost of a nightlight. It’s still sold, still fully open, and still a perfectly good way to learn how mining works. It’s just been quietly overtaken by its own successor.

The straight take

There’s nothing wrong with the Supra. That’s the odd thing about recommending it. The BM1368 is proper Bitmain silicon, the same chip that went into the standard Antminer S21, and AxeOS is the same open firmware you’d get on any Bitaxe. The problem is entirely relative. The Gamma turned up with a newer BM1370 chip that does more hashrate at better efficiency for roughly the same price, which leaves the Supra as the sensible pick only when the sums change. Find one cheap, or already have the heatsink and fan spare, and it’s a bargain. Pay full whack for it next to a Gamma on the same shelf, and you’re leaving performance on the table for no reason.

What the numbers actually mean

0.7 TH/s is a fraction under the Gamma and a fraction over most of what came before it. In lottery terms that’s neither here nor there: either way you’re buying one ticket in a very big draw. Efficiency of around 17 J/TH is decent, a shade behind the Gamma’s 15 but nowhere near embarrassing, and it means the roughly 12W it pulls turns almost entirely into hashrate rather than waste heat. Power that low is the real selling point of any small Bitaxe. You can leave it running around the clock and barely notice it on the bill. One thing to hold loosely: vendors quote the Supra anywhere from 625 to 775 GH/s depending on clocks and cooling, so take 0.7 TH/s as the middle of a band, not a guarantee.

If the lottery angle sounds purely theoretical, it isn’t quite. A hand-sized Bitaxe of this class (a previous-generation BM1366 Ultra, not this exact board, so I’ll be honest about the chip) did solve a full block solo on CKPool back in 2024 and took the whole reward. The Supra’s odds are no different in spirit: astronomically long, but not zero, which is the entire point of the thing.

Overclocking, and where it stops

The BM1368 has headroom, and AxeOS makes it a two-box job: set a core frequency, set a voltage, watch what happens. Stock is around 490 MHz at roughly 1150 to 1200 mV. Owners on r/BitAxe report walking a good chip up to about 650 MHz at somewhere between 1.23 and 1.33V, which lands them 700 to 900 GH/s while the heatsink holds around 50C. That’s a real, useful bump for a board this cheap.

Two things bite if you go chasing it, though, and neither is the one people expect. The first isn’t heat, it’s the hardware error rate, which starts creeping up once you push past 600 MHz. Error shares are wasted work, so there’s a point where more megahertz buys you nothing but a warmer chip. The second is power delivery. Push the board to 20-25W and the little 5.5x2.1mm barrel jack is at the edge of what it wants to pass, and a weak or thin-cabled supply will sag under the current and drop the board into a brownout reboot loop. The fix is a proper 5V/6A supply and a decent cable, not a fancier heatsink. That barrel jack is also the only way in, by the way: the onboard USB-C is for flashing and the serial console, and it can’t feed the chip enough current to mine. Don’t try.

Living with one

Cooling is a non-event at stock. On the Dark Horse pin-fin heatsink and its fan the chip sits somewhere in the mid-40s to mid-50s Celsius, and AxeOS will throttle or cut out well before anything cooks, so you’d have to work at it to hurt one. Overclockers tend to swap the stock fan for a Noctua on a 3D-printed mount and dab fresh paste under the heatsink, which buys a few degrees of headroom, but for an all-day quiet miner you can leave the stock cooler alone.

Noise is the part that surprises people. It’s genuinely quiet, under 45 dB by most accounts and under 40 with a Noctua or an underclock, which is why the Supra gets recommended to beginners over a Gamma that runs hotter and spins its fan faster. You can have this on a shelf in the same room and forget it’s there.

The firmware is the reason to buy any Bitaxe, and it holds up here. AxeOS runs off the onboard ESP32-S3, serves a web dashboard to any phone or laptop on the network, shows you live hashrate, temperature, pool state and your best-ever share, and has an autotune that hunts for a workable clock on its own. The one quirk worth knowing before you unbox it: that Wi-Fi radio is 2.4 GHz only, so a 5 GHz-only network simply won’t see it, and a weak signal shows up as rising rejected shares rather than a clean drop. Get it on a decent 2.4 GHz signal and it’s genuinely plug-in-and-forget.

Who should get one - and who shouldn’t

Get one if the price is right. If you spot a Supra going cheap, or you’re building from a parts bin and already have the bits, it’s a fine little miner that’ll teach you everything a Gamma would. The open firmware means you can tinker to your heart’s content, and it sips power while you do.

Don’t get one at full price when a Gamma is sitting next to it for about the same money. That’s the whole case against it in one sentence. Skip it too if efficiency is your main concern, because the newer chip simply does the job better. For most people buying new, the Supra is the answer to a question the Gamma already solved.