How big a power supply do I need for a Monero mining rig?
For a typical single-CPU Monero mining PC without a power-hungry graphics card, a good 400–550 W power supply is often enough. For a high-core-count workstation or a multi-CPU server, you may need 650–1,000 W or more, depending on the parts. Choose your size from the whole system’s maximum power needs, not just the CPU rating or your usual mining load.
Add up the parts that need power
Monero uses RandomX, a mining algorithm—the work your computer does to help secure the network—that favors CPUs. Your processor is therefore usually the main power user, rather than a bank of graphics cards.
Start with these items:
- CPU: Find its maximum power limit at your chosen settings. Do not rely only on TDP, a heat-design rating that may be lower than actual peak power use.
- Motherboard and memory: Include both, especially if you have a server board or many memory modules.
- Cooling and storage: Count fans, liquid-cooling pumps, and drives.
- Graphics card: Include its potential maximum draw if one is installed, even if you do not use it for mining.
You can check component specifications and independent power measurements. For an ordinary desktop, reserving roughly 50–100 W for components other than the CPU and a dedicated graphics card can be a starting estimate. Servers and heavily equipped workstations need a more careful count.
Leave room above your estimated maximum
A practical target is a power supply rated about 25–30% above your estimated maximum sustained component load. This gives you room for estimation errors, brief power spikes, and modest upgrades.
For example:
- CPU at its configured maximum: 180 W
- Motherboard, memory, drives, and cooling: 70 W
- Estimated total: 250 W
- With 30% extra capacity: 325 W
A quality 400–450 W unit would be a sensible choice for that example, assuming it has the right connectors. A 1,000 W unit would usually be unnecessary.
If you have a powerful graphics card, follow its manufacturer’s power-supply guidance too. Large, brief spikes may require more room than this simple calculation provides.
Understand the number on your wall meter
A power supply’s watt rating describes the power it can deliver to your components. A plug-in wall meter measures that power plus energy lost inside the supply.
For example, if your components use 300 W and the supply is 90% efficient, the wall draw is about 333 W. Use component demand to size the supply; use wall draw to estimate your electricity cost.
Browser mining may draw less power than a dedicated mining program, but do not size your supply around one browser session. Software settings, CPU boost, and other tasks can increase demand.
Check quality, connectors, and server requirements
For a rig running around the clock, build quality matters more than an impressive watt number.
Look for:
- Independent reviews covering safety protections and sustained output.
- Enough EPS CPU power connectors, which feed the processor through the motherboard.
- Strong 12-volt output, which supplies most CPU power.
- The correct physical size and motherboard compatibility.
An 80 PLUS efficiency rating is useful, but it does not guarantee quality. Never reuse modular power-supply cables unless compatibility is explicitly confirmed.
For servers, check the manufacturer’s requirements. Two redundant supplies may be intended to let either one carry the entire load—not to double your usable capacity.
The bottom line
Add up your rig’s maximum component demand, allow sensible headroom, and buy a well-reviewed supply with the right connectors. For many CPU-only Monero desktops, 400–550 W is plenty.
