Should I disable SMT when mining Monero?

You should not disable SMT automatically when mining Monero. Start with it enabled, then compare mining performance and power use with fewer mining threads before changing your computer’s settings. The best choice depends on your processor’s cache, cooling, and whether you use the machine for anything else.

What SMT changes for mining

SMT, or simultaneous multithreading, lets one physical processor core handle two software threads at once. Intel usually calls this Hyper-Threading. Those threads share the core’s resources; they are not two full cores.

Monero uses RandomX, a mining algorithm designed to favor CPUs, the main processors in PCs and servers. Two mining threads on one core can sometimes use that core more effectively. But they can also compete for resources and produce little extra work while increasing electricity use.

That means “more threads” does not always mean “better mining.”

Check your cache before counting threads

RandomX needs about 2 MB of L3 cache per mining thread. L3 cache is a small, fast area of memory inside your processor. If you run too many threads for the available cache, mining performance can suffer.

For example, a processor with eight physical cores, 16 logical threads, and 16 MB of L3 cache has cache capacity for roughly eight mining threads—not necessarily 16.

Use that as a starting point, not a guaranteed best setting:

• Check your CPU’s physical core count and L3 cache size.
• Start around one mining thread per physical core, while respecting the cache limit.
• Try additional threads if you have enough cache.
• Remember that cache layout matters, especially on processors with multiple groups of cores.

RandomX also needs memory beyond L3 cache. Its fast mode uses a dataset of about 2,080 MB. Having enough system memory does not remove the per-thread cache constraint.

Test fewer threads before disabling SMT

Leaving SMT enabled does not force your miner to use every logical thread. A logical thread is one of the processing slots your operating system sees.

If your mining software supports it, reduce its thread count and use thread affinity—a setting that assigns mining work to particular processor slots. This lets you test one mining thread per physical core while leaving SMT available for your other programs.

Compare these configurations:

• SMT enabled with the miner’s automatic settings.
• SMT enabled with one mining thread per physical core.
• SMT disabled in BIOS or UEFI, your computer’s startup settings.

Keep other settings the same. Let each test run long enough for temperatures and mining speed to settle. Record hashrate, meaning mining calculations per second, along with temperature and electricity use. A wall power meter gives a better whole-system comparison than CPU power readings alone.

Choose for your PC or server

For a dedicated mining machine, prioritize hashes per watt: how much mining work you get for the electricity used. Slightly lower speed can be worthwhile if power use drops more sharply.

On your everyday PC, also check responsiveness, fan noise, and heat. Reducing mining threads is often more convenient than disabling SMT for everything.

On a server, disabling SMT affects other applications and virtual machines too. Test their performance before making a system-wide change. In a browser miner, you may have limited control over thread placement, so results can differ from dedicated mining software.

The bottom line

Keep SMT enabled initially and tune the miner’s thread count first. Disable SMT only if repeatable tests show better efficiency, stability, or usability on your particular machine.