With regards to increasing RAM voltage, I had it set around .045v above spec just to see and the stability didn't improve. The guys over at Anandtech forums unfortunately couldn't offer much more insight into the issue either, besides repeated tests in various configurations, which I'd already done, and updating the BIOS, which I also did.
The PSU was faulty, that much is clear, so whether or not that was a major contributing factor, I'm not sure. In any case, I RMAd the lot and the courier came to pick it up today. It'd be nice if the supplier gives me a fault report, but I'm not holding my breath. Just looking forward to having a working computer here by the weekend.
Thanks again for your help, I'm just sorry I won't have any answers to help other sufferers of an issue like this.