Verdict: Cool, quiet and efficient
Corsair is one of the biggest and best brands of overclocking memory, and it's now branching out into PSUs. Like most PSU brands, however, Corsair doesn't manufacture the CMPSU-620HXUK, turning instead to the experts at Seasonic, makers of the CPC Elite-listed S12-600.
The Corsair is a modular PSU, which means that you only need to plug in the cables that your PC needs, making it far easier to build a tidy PC. It's rated at 620W, which is output via three 18A 12V rails and the usual 3.3V, 5V, -12V and 5VSB rails. 12V1 supplies power to the motherboard and CPU plugs, 12V2 supplies the first PCI-E plug and the first two 5-pin modular connectors, while 12V3 supplies the second PCI-E plug and third, fourth and fifth 5-pin modular connectors. The Corsair's interior is kept cool by a 120mm fan that sucks in air at the bottom, and expels it at the rear through a hexagonal grid-shaped grille, which is the most efficient shape for achieving good airflow.
At 50 per cent load, the CMPSU-620HXUK delivered a stable voltage on all its rails, and was efficient, requiring just 356W to generate 296.8W. This means that it's 83 per cent efficient, which is well above the 65 per cent efficiency required by the ATX spec. At 100 per cent load, it also proved efficient, averaging 82 per cent, but the output from its 5V rail dropped to 4.68V, just below the 4.75V required by the ATX spec, which may be a problem if you have a lot of disk drives.
CONCLUSION
The Corsair is one of the quietest 600W+ PSUs that we've tested but, unfortunately, it isn't capable of delivering a stable voltage on its 5V rail at 100 per cent load. However, given this, and its decent efficiency, it could still be worth checking out as long as your PC doesn't have lots of disk drives.
