OCC has published a new review on the Xigmatek NRP-PC502 500W

In order to meet the requirements of the 80 Plus Bronze standard, the power supply must run with a power factor of 0.9 at 50% loading and an efficiency of 82% at 20%, 85% at 50% and 82% at 100% loading. All 80 Plus testing is done at 115VAC and 60Hz, probably due to the fact that it is a USA-based organization and all power supplies I have tested at 15VAC/60Hz will usually result in a pass at 230VAC/50Hz. The Xigmatek doesn't quite make the mark following the OCC testing methodology, but it's close, missing the 80 Plus Bronze requirements by two percent at 471W loading at 110VAC. I would expect most good quality power supplies to maintain their power factor at or above 0.9 for any load above 20% of their rated maximum. It's disappointing to see a power factor of 0.88 at 110W loading on 230VAC, but it meets the ATX12V V2.2, so technically speaking it's still a pass.

Xigmatek NRP-PC502 500W Power Supply Review