The Tagan has a lot of potential. It has a solid design, good components and high efficiency. The 12V and 5V output regulation is some of the best I have seen. Where it falls down is on 3.3V output regulation.
As a saving qualifier, the 3.3V performance was fine at defined PC loads this power supply is likely to see, but if you are paying for 880 Watts, you want to know it will deliver on output. Well, unfortunately, it appears the Tagan TG880-U33II SuperRock comes up a bit short in that respect.