xfx 680 i lt sli
c2d 6750 2.66Ghz
pny nvidia 430 video
corsair xms 2 ddr2 6400 800mhz
500Gb WD HDD (new)
win xp pro x64 (fresh install)
all setting are factory at present. when i have the fsb (1333 stock) at 1500 with a cpu speed of 3.0 and the memory unlinked and at stock settings(800mhz voltage auto, ratio auto), all voltages set to auto, i can run stress tests on the cpu for days and never reach a temp higher than 57Celsius using prime. no crash, no error. nothing. if i add ram to the testing or even if i use memtest by itself without any other program running, pc freezes as soon as the ram test starts. open bios and set defaults and i can test the memory as hard as i please. no issue. any ideas what may be the problem? also i used to be able to run this cpu at 3.2 and now it won't even post past 3.0. any ideas?
thanks for the response. i do suspect the northbridge chip. i think the thermal conductivity is poor between the chip and heatsink. over the last year or so it has given me issues operating the fsb over 1500Mhz. now it absolutely will not operate over that. any attempt to push it higher and the bios goes into safe mode. i have de-tuned the system back to stock and am looking for a replacement. 775's are kinda dinosaur these days tho...
is that safe? the ram i am using is the corsair xms 2 "c" revision 2x2Gb. it is rated at 1.8v. i only ask because i have no direct cooling for the ram at this point and these sticks are only a few days old. i would hate to fry them. thanks for the suggestions.