@akshyat : Maybe something is dying ... since i remember u mentioned that the m/b had problem with particular modules , which were absolutely absent in most other cases , u could have already been using a faulty piece of hardware (had my days with one too) ... did u try to update the bios ?? or ru facing the problem after updating the bios ??
Also .. post the complete config .. makes it much easier to judge ..
Also , u mentioned u oc'ed the CPU ... ru sure ur RAM is able to tolerate the OC ... also.. .. ru using A8N-E ?? .. then see if 2T makes any diff.
Also .. the X1900XTX is pretty much bottlenecked by the X2 4800+ in most cases ... and i don't think ur oc'ed CPU is better than that CPU .. ur CPU can actually turn out to be a huge bottleneck , even with the oc ..