After playing around for a month or so with water on a Skt-T, I've come to a pretty clear conclusion that the area around the socket needs air. Folks with Heatsinks may not see this as they have a steady stream passing over the CPU AND the caps and surrounding area. But if you have a WaterBlock, there's no air and may need to find some method to get a slug of air around there somehow.
This may be a design issue with just the Abit AA8 and the Asus Premium's, but I've noticed it on both. They've both OC'd very well, but wouldn't be stable with a high OC after a couple days. On accident, I left the case's side open and my big fan in the house happened to be blowing in my direction and it stayed running all week with no problems.
I took a laser temp gauge and noticed all the caps and transistors around the CPU where very hot. I took away the fan, and it occured again...instability after long up-times even though the core temps looked great. Keep in mind this is occuring after 4 days or so, so it's not a huge hit or anything. Especially if you shut down regularly.
I ordered another crossflow fan (lost the other) and I'll try and follow up after a steady week of up-time *crosses fingers*. I figured you all should know this if you didn't already. I had hopes of eventually only running one fan, and that would be on my Radiator. This now sounds like I'm going to have to keep the crossflow on low (21dB) all the time and squash that idea. Not much of a bummer, as it was pretty much a pipe dream.
Oh ya, if you don't OC, then I don't think this should be a problem. I've ran the Abit AA8/550 for 2 weeks after an hour of burn-in no problems. It's just after ramping up 255+ that I see it not wanting to stay up. And may be another reason that the Abit Fatality is a good purchase with all it's fans (I'll settle for a ducted crossflow and the awesome Asus, thank you