Verdict: Too quiet to be true

The 600W SilenX is one of the more expensive PSUs in this month's Labs test, so we were expecting it to be extremely quiet, stable and efficient.

The maximum claimed output of 600W is split across the primary rails, with 32A on the 3.3V rail, 42A on the 5V rail and a hefty 36A on the 12V rail. We're not convinced that such a powerful single 12V rail is a good idea, as the latest ATX spec cites that 'in cases where current requirements are greater than 18A, a second 12V rail should be made available'.

Although the SilenX has support for both 20- and 24-pin motherboards, and even an 8-pin EPS12V connector, it has no PCI-E support, just eight Molex, two FDD and two S-ATA connectors. Cooling is provided by a near-silent 80mm fan, which, SilenX claims, produces just 14dBA.

Unfortunately, this slow-spinning 80mm fan is unable to keep the SilenX cool and, after just a few seconds with the 3.3V and 5V rails at 100 per cent load, the PSU shut down. Although it switched on again after being left to cool down for a while, we were unable to draw the claimed 36A from the 12V rail.

Not surprisingly, it isn't possible to keep a genuine 600W PSU cool with a single 80mm 14dBA fan, and the SilenX is only capable of delivering 449W over a limited period.

• 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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• Asus EAH4870 TOP - Graphics cards
• Creative Sound Blaster X-Fi Titanium Fatal1ty Pro - Sound cards
• Multiwinia - Games
• Zotac GeForce GTX 260² - Graphics cards
• Sapphire Radeon HD 4850 X2 - Graphics cards
• Scan 3XS X58 Core i7 - Desktop PCs