OCC has published a review on the Ultra X4 600W Power Supply

The Ultra X4 600W power supply performed well in some areas, but performed poorly in others. The DC voltage load regulation is on a par with many high end power supplies but the noise/ripple levels are in excess of the limits laid down by the ATX12V V2.2 specification which makes this power supply hard to recommend to the overclocking community. The failure to meet its claimed 80 Plus certification following the OCC testing methodology, excessive noise/ripple on the main DC rails, and lack of technical information make this power supply more suitable for the mainstream market.

Ultra X4 600W Power Supply Review