So to start with I used 2x1gb of the XMS2 PC-6400 (guaranteed to run at 1066mhz/2.1v/C5.5.5.15) in my Rampage Formula. I ran this for about a year with no problem at all. I then upgraded to 2x2gb of the same stuff and was unable to boot into windows @ 1066mhz. So I left it at 800mhz and after about a month vista started BSOD'ing regularly which lead me to running memtest86+ which revealed 1000's of errors on one of the modules. So I RMA'd both sticks and bought another 2x2gb of the same RAM in preparation to use 8gb. These 2 sticks ran fine for a week including a heavy session of gaming at a LAN party under 1066mhz/2.2v/C5.5.5.15. I then receive my other 2 modules and plop them in. After running for 2 days at 1066mhz/2.2v/C5.5.5.15 my PC crashes with a similar memory BSOD but memtest turns up 0 errors.
The main query is, why does my system remain unstable souly because of my RAM (even though it's clocked at it's normal 800mhz) when I overclock my CPU to 3.2ghz? It refuses to run games and crashes soon after playing.