Is a second Bitaxe worth it? The honest calculation for stacking hashrate

By Dominik Lederer, Founder, Hardware Engineer & Solo Mining Expert · August 10, 2026 · 7 min read

The most common question I receive after a sale doesn't come on the first day. It comes after about six weeks. The device is running, the dashboard is set up, the best value in AxeOS has been beaten twice, and then an email arrives with one sentence: I'm thinking of getting another one.

I like this email. It means the hardware has done its job. But it's also the email that takes me the longest to answer, because the honest answer has two parts, and the first is uncomfortable.

Does a second Bitaxe really double the block chance?

Yes. Completely, linearly, without deduction. The probability of a solo miner finding a block within one year follows the formula: own hashrate times seconds per year divided by difficulty times 2 to the power of 32. In this formula, the hashrate appears exactly once, in the numerator. If you double it, the result doubles.

Specifically, with the difficulty from the retarget on August 8, 2026 (Block 961,632, value 127,479,855,693,691):

• 1.3 TH/s: approx. 1:13,355 per year
• 2.6 TH/s (two devices): approx. 1:6,678 per year
• 3.9 TH/s (three devices): approx. 1:4,452 per year

That's the good news, and it's more important than it sounds. In pool mining, your share is cut by fees, minimum payouts, and variance smoothing. In solo mining, every additional terahash gets exactly the weight it deserves. No middlemen, no tiers, no bulk discounts in either direction.

Does solo mining become more economical with more devices?

No. And that's the part you should hear before you order.

A Bitaxe Gamma 601 consumes about 17 watts. That's 148.9 kilowatt-hours per year and, at 0.35 euros per kilowatt-hour, about 52 euros. The statistical annual yield is 13.20 euros (block chance 1:13,355 times block value of approximately 176,300 euros, which is 3.125 BTC plus transaction fees at 56,404 euros per BTC, depending on the exchange rate, as of August 10, 2026). Ratio: 3.95 euros electricity for one euro expected value.

Now two devices. Electricity 104 euros, expected value 26.40 euros. Ratio: 3.95 to 1. Exactly the same.

Out of curiosity, I calculated this to the extreme. How many devices would one need for one block per year to be due on average? Answer: 13,355 units. At 129 euros per device, that would be about 1.72 million euros in acquisition costs, a connected load of 227 kilowatts, and about 696,000 euros in electricity per year, for an expected yield of 176,300 euros. The ratio? 3.95 to 1. It never changes.

So, anyone hoping to achieve profitability through sheer volume is calculating in the wrong direction. Industrial mining doesn't work because there's a lot of it, but because it buys electricity for two to four cents. This exact leverage is missing in the living room, and no amount of devices can replace it.

What does more hashrate really cost?

This table compares four ways to achieve more hashrate. All prices are our current store prices, all consumption values are from the respective product data, and the electricity price is assumed to be 0.35 euros per kilowatt-hour.

Setup	Purchase Price	Hashrate	Electricity per Year	Block Chance per Year
1x Bitaxe Gamma 601	129 Euros	1.3 TH/s	approx. 52 Euros	1:13,355
2x Bitaxe Gamma 601	258 Euros	2.6 TH/s	approx. 104 Euros	1:6,678
3x Bitaxe Gamma 601	387 Euros	3.9 TH/s	approx. 156 Euros	1:4,452
1x NerdQaxe++ Rev6.1 (103 W in overclock)	449 Euros	up to 6 TH/s	approx. 316 Euros	1:2,894

Purely calculated on hashrate per euro purchase price, the NerdQaxe++ wins with 13.4 gigahash per euro, significantly ahead of the second Bitaxe with 10.1. This is where most purchase advice on the internet ends, and this is exactly where the interesting part begins.

Because hashrate per euro is the wrong metric. It ignores operating costs, and they continue every day for every device. The Bitaxe Gamma 601 operates at 17 watts for 1.3 TH/s, which is about 13.1 joules per terahash. The NerdQaxe++ is, according to product data, between 14.66 and 16.5 joules per terahash. The smaller device is more efficient per terahash. If you are looking for the block chance with the lowest power consumption per chance, buy the second Bitaxe. If you want the highest chance in the smallest shelf space, buy the NerdQaxe++. Both are legitimate goals, they just exclude each other.

Two devices with 1.3 TH/s or one device with 2.6 TH/s?

Mathematically: no difference. The block chance depends solely on the sum of the hashrate. Whether this sum comes from one chip or two is completely irrelevant to the blockchain. The best value in AxeOS also behaves statistically the same, because it depends on the total number of hashes checked, not on their distribution across enclosures.

Practically, there are three differences, and all three favor two devices:

Redundancy. If your only device fails, your hashrate drops to zero. If one of two fails, it's at 50 percent. The financial damage in both cases is tiny, a day of downtime costs about 3.5 cents in expected value, but the weeks waiting for a power supply to be returned feel much more relaxed with a second device running.

Two pools simultaneously. You can put device one on one solo pool and device two on another. This means your availability no longer depends on a single operator's infrastructure. If you want to know the price of this security: fee differences between solo pools for this hashrate are in the range of cents per year; downtime costs more.

Thermal reserve. Two devices at factory clock run cooler, quieter, and longer than one device pushed to 2.6 TH/s by overclocking. How little overclocking pays off in terms of hashrate, I disclosed in the calculation for the cooling upgrade, including the point where I advise against the purchase.

When is a second Bitaxe still worthwhile?

The most honest reason isn't in any table: because the first device works and you now understand what's happening. This isn't a calculation result; it's curiosity, and curiosity is a completely legitimate reason to buy. I didn't buy my second device because an Excel cell turned green either.

What you shouldn't expect, however, is that the waiting time becomes human. An expected value of 6,678 years instead of 13,355 are both beyond any lifespan, and for those who want to see these numbers clearly sorted for the first time, they can be found in the expected value calculation for the first device. Solo mining does not become an investment through quantity. It becomes a slightly denser lottery ticket that incidentally produces knowledge.

In the community, running multiple devices is called swarming. The term sounds like scaling, but in reality it describes a hobby that needs space: power outlets, network ports, shelf space, and a household that doesn't raise an eyebrow at three humming aluminum blocks on the dresser.

What does a second miner offer compared to other leisure expenses?

Criterion	Two Bitaxe Gamma	Traditional Lottery	3500-W Industrial Antminer
Odds of winning per year	Approx. 1:6,678 for a full block of 3.125 BTC plus transaction fees. The chance runs 24 hours a day without you having to do anything.	Only exists on the day you buy a ticket. If you don't play, you get exactly zero, and last week's ticket never counts again.	Significantly higher, but practically only usable in a pool. There you get shares instead of a whole block, settled through a third party.
Running costs in a home office	Approx. 104 Euros in electricity per year for both devices combined, about 8.70 Euros per month. Runs on any standard outlet without modification.	No electricity, but money that's gone after the draw. Nothing remains on the shelf.	Over 10,700 Euros in electricity per year at the same rate, plus heavy current, noise protection, and waste heat that no living space can accommodate.
Drawer danger (Boredom factor)	Low. Two displays with two separate best scores create a small competition on your desk, and there's always something to adjust.	High. Nothing happens between submission and drawing, after which the ticket is paper.	Very high in a living space. The device is too loud to sit next to and ends up in the basement, garage, or hosting.
Learning effect & hands-on blockchain fascination	Very high. With two devices, pools, clock rates, and cooling solutions can be directly tested against each other instead of believing forum claims.	None. You learn nothing about numbers that you didn't already know.	Present, but at a high cost and usually in a place where no one voluntarily stands.

"A second Bitaxe doubles your chances and doubles your electricity bill. What it doesn't do is turn a hobby into an investment. Those who understand this buy it for the right reasons." Dominik Lederer, Founder Polarblocks

Frequently Asked Questions about a Second Bitaxe

Can I run two Bitaxes with one power supply?

Not recommended. Each device temporarily draws significantly more than its average value during overclocking, and a shared power supply will cause both devices to crash simultaneously if it can't keep up. Two separate power supplies are inexpensive and halve the risk.

Do I need two Bitcoin addresses?

No. Both devices can use the same payout address in the Stratum User field. Separate addresses are only useful if you want to keep the devices distinct for accounting purposes.

Do two devices in the same pool count together?

For block chance, yes, because both can independently submit valid blocks and their chances add up. They are not combined into a single effort; each device searches on its own.

How much louder will it be with two devices?

Two identical sound sources mathematically result in about 3 decibels more than a single one, not double. At factory clock speed and with proper cooling, this remains in the order of a quiet refrigerator.