Verdict: Quiet, efficient, stable and better connected than the KGB

In contrast to all the other companies whose mid-range PSUs we tested, with the exception of FSP, Seasonic is the only true manufacturer of PSUs.

Seasonic's full control of the design and manufacturing process has clearly given the S12-500 an advantage and, as a result, it's brilliant. Seasonic rates it at 500W, which is split into 30A on the 3.3V and 5V rails, with two 12V rails producing 17A for 12V1 and 16A for 12V2. There's a multitude of power cables, including support for both 20- and 24-pin motherboards, and even 8-pin EPS12V motherboards. What's more, in addition to the usual Molex, FDD and S-ATA plugs, there are two PCI-E power cables just begging to be connected to a pair of graphics cards in SLI.

Seasonic PSUs are renowned for their incredible efficiency, so it's no surprise that the S12-500 can be cooled by a near-silent, temperature-controlled 120mm fan. At 100 per cent load, the efficiency didn't drop below an astonishing 82 per cent. This means that it only required 601W to produce 493W, which is about 100W less than the Ultra XCONNECT 500W consumed for the same output.

As a Premium Grade Approved award winner, it should go without saying that the S12-500 delivers rock-solid voltages at all levels, but it's more than just a stable PSU; it's also quiet, efficient and extremely well connected. The only problem with it is that the 600W Seasonic costs only £9.39 more.

• Cases - 21st November 2008
• Motherboards - 24th October 2008
• Gaming Headsets - 26th September 2008
• Dream PCs - 24th September 2008
• Headphones - 12th September 2008
• Media PC components - 22nd August 2008
• PSUs - 14th July 2008

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