Undervolting
Undervolting is dropping chip voltage below the factory level. Power draw falls faster than hashrate, so the joules per terahash come down.
What undervolting is
A chip's power grows roughly with the square of the voltage, while hashrate follows frequency almost linearly. That gap is where undervolting earns its keep: a step down in volts cuts watts more sharply than terahashes.
Every chip has its own floor. Push the voltage too low and you get hardware errors, board restarts and unstable hashrate, with the weakest chip on the board giving up first. That is why in practice undervolting goes hand in hand with autotuning, which finds that floor for every chip on its own.
It pays off most where the rate is expensive, the summer is hot or the wiring is weak. Fewer watts means less heat and slower fans, so the noise drops along with the power bill.
The ready-made eco modes in custom firmware are exactly this, undervolting plus tuning: draw falls by about a third, hashrate by a fifth, and on expensive electricity that trade comes out ahead.
Quick reference table
| What goes down | chip voltage below the factory level |
| Why it pays | watts fall faster than terahashes |
| Main risk | hardware errors and board restarts |
| What to pair it with | autotuning, it finds the chips' floor |
| Who needs it most | expensive rates, heat, weak wiring |
How to lower the voltage
Start from the firmware's ready eco profile, not from hand-typed figures: it has been proven on thousands of boards.
Watch the hardware error share after every step. Rising errors eat the gain sooner than you will see it in watts.
Test stability in days, not minutes. A board that crashes once a night earns less than a stock one.
Remember the power supply: at reduced draw it runs an easy life, which is a bonus to its lifespan, not a reason to fit a weaker one.
An example in figures
An ASIC at 100 TH/s and 3250 W is 32.5 J/TH. An eco profile with undervolting gives 80 TH/s at 2300 W, which is 28.75 J/TH. There are fewer terahashes, but each one costs less, and at an expensive kWh it is the second option that brings in more money per month.
Related terms
Where to go next on the site
Software
- Software firmware
- Bitmain Stock Firmware firmware
Numbers
Questions and answers
Does undervolting harm the hardware
The opposite: the chips run cooler and the fans slower. The only risk is instability at too low a voltage, and the cure is a step back up.
How undervolting differs from eco mode
Eco mode is a ready preset built from undervolting and reduced frequency. Manual undervolting does the same thing, except you pick the figures instead of the firmware author.
Is it worth undervolting on cheap electricity
Usually not: with a cheap kWh terahashes are worth more than watts, and stock or an overclock pays better. Undervolting is a tool for expensive rates.
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 .