BFG MX Series 550W PSU

Results

The MX Series 550W is quite promising as it delivered all green voltages, but when it's fully loaded the 5V and 12Vs do drop quite a bit. They do stay within the ATX specification, though.

The power factor correction is consistently above 90 per cent and mostly in the high 90s, and for 50 to 75 per cent load (the optimum load area), the efficiency is a decent 85 per cent. Either side of this drops closer to a high 82/low 83 per cent which is a little on the low side. The effect on voltage and efficiency clearly shows that at its full 550W the design is being pushed to the limit.

With just its single sleeve bearing fan, the MX Series is really very quiet, albeit still audible so marginally louder than the dead silent Be Quiet! Dark Power Pro, and certainly comparable to the OCZ ModXStream Pro. Unlike the OCZ though, the 12cm Globe Fan is of higher quality with a better balance, and even after 30 minutes at 100 per cent load the power supply not only survived, the rear 80mm fan was still not spinning!

We recorded the maximum internal temperature right behind the power socket, where there's no vents for hot air to escape, at 67ºC, but mostly the internal temperatures ranged between a healthy 40 to 50ºC.