EP-9NPA+Ultra and 20pin ATX

I haven't had any, i have an antec 450 truepower and am using an adapter, running great

Nope....you should be just fine....great psu btw.

Lots of discussion on that one, from what I've read, 20 pin ATX is not a good idea with pci express because even a low end card can draw a lot of power and may be too much for your power supply with the other stuff in the box already tugging on that branch. The new BATX standard is also dual rail on the 12V branch, I just had this argument with someone, anandtech says not a good idea but considering what a good power supply costs these days I guess your pocketbook is going to be the driving factor. Every once in a while compusa puts their 530W BATX dual rail on sale for 40 bucks instead of the usual 70, I sure wouldn't want to risk a unstable system for a lousy fourty dollars. My two cents anyway, SLI is of course another matter entirely then you're really talking some heavy draw.