Short answer: a home server spends most of its life at light load, so pick a smaller, well-built unit that’s efficient at low power, with enough SATA connectors for your drives. A big gaming power supply is often the wrong choice.
Why it’s different
A gaming PC spends hours at medium to high load. A home server or NAS runs all day, mostly idle, with short busy spells. Efficiency at very light loads matters far more, because those are the hours that add up.
Light-load efficiency
Efficiency drops at very light loads, and some units drop more than others. Lab reviewers flag it when it’s weak. For example, HWBusters noted weak light-load efficiency on the Seasonic Focus GX V4 and modest light-load efficiency on the Corsair HXi (2025). Both are fine for gaming, but there are better choices for a server.
Cybenetics tests across many load levels and includes standby power, so its reports show light-load behaviour that 80 Plus misses. See Cybenetics ratings explained.
What it costs to idle
A server drawing 50W around the clock uses about 438 kWh a year at the wall at 100% efficiency. At 17 cents per kWh, a unit running at 85% efficiency at that load costs about $88 a year. At 75%, it’s about $99. Small differences add up when a machine never sleeps.
What to look for
- Right size. Add up drives and processor at full spin-up and leave some headroom. Many servers need well under 650W.
- SATA connectors. Count your drives. Each SATA cable usually has several plugs.
- A quiet or fan-off mode if it lives in a living space. See zero RPM fan modes.
- A long warranty. It will run more hours than a gaming PC.
- A UPS to protect the drives from power cuts. See what to do after a power surge.
Drive spin-up
Hard drives draw extra power for a few seconds as they spin up. With many drives, that start-up moment can be the highest draw of the day. Check your drive’s spec sheet, and leave room for it when sizing.
ATX12VO
Intel’s ATX12VO standard aims to cut idle power by moving some conversion onto the motherboard. It needs a matching motherboard, and it’s still rare in home builds.
- Compact, 650W · Tier ASeasonic Core GX ATX 380 Plus Gold · Fully modular · ATX · 650/750/850WA smaller, well-built unit. The fan always spins.Check 650W price
- Quiet, efficient · Tier Bbe quiet! Pure Power 13 M80 Plus Gold · Fully modular · ATX · 750/850/1000/1200WCybenetics rates its efficiency Platinum, according to HWBusters.Check 750W price
Questions
What wattage do I need for a NAS?
Usually much less than a gaming PC. Add up drives, processor and spin-up, then leave headroom.
Is a bigger power supply bad for a server?
It can be less efficient at the light loads a server runs at most of the time.
Does my server need a UPS?
I’d use one. A sudden power cut can damage data on drives.
How many SATA connectors do I need?
One per drive, plus any fan or lighting hubs. Check how many each cable carries.
Is 80 Plus Titanium worth it for a server?
Titanium sets a requirement at 10% load, so it’s more relevant to light-load use than other levels.
Sources
- HWBusters: the story behind Cybenetics (ETA requirements)
- Intel: new ATX power supply specifications
- HWBusters: be quiet! Pure Power 13 M 850W review
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