On the whole the Ultra X4 1050W performed very well. The DC voltage load regulation was very good with little fluctuation from zero to full load. The noise/ripple levels although within the limits set down by the ATX12V V2.2 specification were a little higher than I would like especially on the 12V rail. The Ultra X4 1050W marginally failed to maintain the minimum level of efficiency of 80% as required by its 80 Plus certification giving 79% at 20% loading on 110VAC. The power factor dipped below 0.9 which is very unusual even on some mid range power supplies.