Let's start by looking at the wattage recorded. Under full stress, it peaked at 509.9W which is probably a lot higher than you would get during normal extended usage. So the power supply is ideal for a mid-high end computer sporting a single GPU. It did not even break a sweat under the extreme testing conditions. While the power supply is SLI certified, I would only recommend it for mid-range GPUs sporting a single 6pin power connector. A crossfire 4850 setup or SLI 9800gt should be the maximum that this power supply could cope with.

The +3.3V rail was out by 0.1V at idle and 0.08V under load, which is still acceptable. The +5V rail was pretty much bang on. The +12V rail on the other hand was on the high side. At idle it was 0.49V higher than it should have been but under load, it lowered to a more acceptable level.

Despite these high readings, general usage was stable and there were no crashes or issue at all. Even while recording the voltage readings, they did not fluctuate and remained stable.

Noise
The 135mm fan helped keep the power supply cool and quiet although I did notice a slight whirring noise at one point. Overall it is a very quiet unit and will not distract you at all.

Efficiency
Rated at 82%, it is a bit on the low side compared to many modern power supplies, but these cost upwards of £80. In that sense, the OCZ Fatal1ty is a good compromise and compared to the Enermax Revolution 85+, it only consumed 20-30W more.