If you are in the market for a power supply in the 650W range, I certainly could not recommend this one for a high performance system. Like its name suggests (Atrix 500T), 500W is probably a more realistic maximum than the stated 650W. The efficiency and power factor are very poor and the failure of the unit to maintain the 3V3 and 5V0 lines at heavy loads, just reinforces my case. I should also bring to your attention a really irritating noise coming from the unit at high load - a sure sign of a stressed out low-end power supply. I am convinced this unit would fail within a short period of time if constantly loaded above 500W. The casing of the power supply got far warmer than the temperature of the air leaving the enclosure suggested, but with such a poor efficiency of 57.7%, this is not surprising.