First of all grats on getting it working. at work we had one that had similar problems with the 8.1 beta, we unplucked one of the ram blocks and it installed fine, funny thing was that it ran win 8 just fine. not that I have any prof and it was a one timer but on that PC 8.1 was touchy with ram. after we nailed the problem both blocks was tested with memtest = no errors. proberly a ram controller issue, but these things takes forever to locate.