lol 941 on the core, nice clocks

I'v flashed my bios's several different times and found if I change the mem frequency the screen occasionaly goes blank.. I'm guessing VRM's over heating? I can get the cores upto about 850ish on stock voltages but am unsure of max safe voltage so havnt touched voltages yet..but want to go as far as the stock cooler will take me.. might purchase some water cooling if I like the results