AsicBoost
AsicBoost is a way to compute SHA-256 with fewer operations. The chip does the same job for less energy, and the network accepts the result like any other.
What AsicBoost is
The block header is hashed in two passes, and part of the first pass does not depend on the whole header. AsicBoost reuses that piece of work across many attempts at once by cycling through the block's version field. Less repeated work, fewer watts for the same hashrate.
The open variant, known as overt, works through version rolling: the ASIC agrees with the pool that it will flip version bits, and the network can see it. There was also a covert variant that made plenty of noise back in the day, but today's practice is the overt one, backed by the pools.
On older generations, enabling AsicBoost through firmware brought a real gain: around 13 percent in efficiency on the S9. Modern chips are designed with it from the start, so there is nothing to switch on with a new ASIC: it comes enabled from the factory.
For a miner the takeaway is simple: the pool has to support version rolling. Every major pool has for years, and no separate setting is needed, but with an exotic pool or old firmware it is worth checking the connection log.
The short version
| What it does | removes the repeated part of SHA-256 work |
| Working variant | overt, through version rolling |
| Gain on old chips | around 13 percent on the S9 |
| On new chips | enabled from the factory |
| What the pool needs | version rolling support |
What it means in practice
On a modern ASIC there is nothing to enable: the savings are already in the chip and in the spec sheet numbers.
On old S9-era hardware, look at custom firmware: AsicBoost is a large share of the gain it delivers there.
Check pool support in the log: a version rolling line in the Stratum handshake means everything works.
Don't expect miracles from the word in a firmware description: on anything newer than the S9, an AsicBoost mention is marketing, not extra gain.
An example from history
An Antminer S9 on stock firmware next to the same one with overt AsicBoost enabled: identical hashrate, consumption down by roughly 13 percent. For a farm running about a hundred S9s that was the line between profit and shutting down, which is why AsicBoost firmware spread across the whole market back then.
Related terms
Where to go next on the site
Software
- Software firmware
- HashCore Toolkit firmware
Algorithms
- SHA-256 algorithms
Questions and answers
Is AsicBoost fair to the network
The overt variant, yes: flipped version bits are visible to everyone and accepted by the network. The old disputes were about the covert variant, which is not used today.
Do I need to enable AsicBoost on a new ASIC
No, chips of recent generations hash this way out of the box. Switching something on was a thing on S9-era hardware.
Why does my pool mention version rolling
That is overt AsicBoost in action: the pool confirms your ASIC may change header version bits. All good, that is how it should look.
How the terms connect
Every link in the chain is clickable. Orange marks where you are now.
Looking for an ASIC miner
The catalog holds 212 models. You can compare them by hashrate and by joules per terahash, then plug your own rate into the calculator and see what stays in your pocket.
Page written and checked by Denys Klimchuk. Updated .