Hmm then you just have a really bad sample.
Unless you have a dodgy PSU.
The PSU is from Corsair, 750W, and I have only a single GPU, so the power can't be insufficient. It just a bad sample, I guess. Anyway, 4.4 isn't bad, it's a pretty decent overclock, but with an average chip, I bet I could go to at least 4.8 with this cooler.