Unstable oc with new HSF

[lee87]

Hi, I got a new HSF (Thermaltake blue orb II) to replace the stock one on my X2 3800+. The temps are now lower but not great - 50c load. If I overclock the cpu to anything over 2.5 ghz it is unstable. I could get it to 2.65ghz using the stock hsf and this was with higher temps (59c).

Does anyone know why I can't overclock now that the temps are lower with my new hsf.

Thanks

 

[lee87]

I used some AS5 but I didn't clean the cpu as I didn't know what to clean it with. Would this make a difference?
The temps are lower at both idle and load. I'll try reseating the HSF tomorrow.

 

[lee87]

I've just removed the old paste and put some AS5 on and the temps have gone down a bit. I've tried to overclock again and I can get it to 2.63ghz .
This was about the same oc I got with my stock heatsink.
Any higher and it doesn't even get past the post screen. This must be the limit for my cpu.

Thanks for the help