Verdict: Rock-solid and efficient, but too noisy for a home PC

We wish Enermax would stop naming its PSUs so cryptically; although the EG851AX-VH(W) name suggests that this is an 851W PSU, it's actually a 660W unit.

The 12V1 rail powers the motherboard and is rated at 14A, the 12V2 rail powers the CPU(s) and delivers 18A, while the 16A 12V3 rail and 14A 12V4 rails supply power to the other connectors. There are eight Molex, two FDD, two S-ATA and two PCI-E connectors.

Adaptors are provided so that the PSU can be hooked up to 20- and 24-pin ATX motherboards, while the additional 8-pin EPS12V connector means it will work with dual-CPU and dual-core CPU motherboards too. The interior is kept cool by two temperature controlled 80mm fans.

As you'd expect from a server-orientated PSU, the Enermax is perfectly stable, even when we drew the full 480W from the four 12V rails. It's also very efficient, averaging 80 per cent at full load, which means it draws just 816W from the mains to produce 651W. At 100 per cent load, the two fans are very noisy. However, the Enermax isn't quite as noisy as the Cooler Master Real Power 550W.

While this Enermax has lots of power to spare, and is very stable and efficient, it's still too noisy for a home PC.

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