what can be wrong with my o/c?

[ntpphong]

i'm using corsair xms pc2700 512MB cas2 rated. i'm testing it at 159x13 at 1.65Vcore and it seems to work fine with prime95, but when i get up to 166x13 and even pushed to 1.7Vcore (1.65 kept rebooting when loading windows) and ran prime95 it shows error after the first 30seconds of test.. i think with error in checksumptio or something like that.
what can be wrong with my o/c? or is that my mobo that fks up? before that i had the problem too but i thought it was my XtremeDDR that is incompatible with my mobo. about the RAM testing... i have it set to optimal, but in chip-configuration i have it set to manual with 2-2-2-5 and 1t at auto. i can't find any place to up the memory voltage so i didnt mess with that yet.

[juliendogg]

might try 3, 3, 3, 5 just for kicks but your ram should be fine. probably you just need to up the voltage on that chip a touch. if you got reboots at 1.65v and errors @ 1.7 maybe 1.75 could work for ya.

[Pinky]

Originally posted by juliendogg
might try 3, 3, 3, 5 just for kicks but your ram should be fine. probably you just need to up the voltage on that chip a touch. if you got reboots at 1.65v and errors @ 1.7 maybe 1.75 could work for ya.

Think julien hit the nail on the head. At 166mhz bus you're pushing that memory past spec. Just like with a processor running at higher-than-default speeds, you will need to add some voltage to stabilize the overclock. 2.8 or 2.9 vdimm should work. I usually don't push more than 3.00v through my memory, it's expensive and I'd hate to turn the PC on in a month and find that although I could run 3.2v fine for 29 days, I couldn't for 30.

If you can't (or are unwilling to) raise the vdimm, Juliendogg's suggestion to relax the memory timings should help.

[ntpphong]

but 166 isnt past the spec since it's pc2700 and 166 is the least it should do, isnt it?

[tragic_monkey]

try 166x12.5 it may be your cpu limiting you

[ntpphong]

can't go down to 12.5 since it' still locked. the lowest i can go is 13. i dont think its a cpu-problem