I have recently finished my first proper new build with an E8400 and an 8800GT. I fitted an Arctic Cooler Accelero and a 12cm fan at 1000RPM to the 8800GT and used my previously bought Zerotherm CF900 on the CPU CF900 Low Profile Copper Temp Controlled CPU Cooler The 8800GT now idles at 44 and under under full load (rthdribl) hits 68, which i am very happy with, as 68 was the idle temp with the stock cooler. However my E8400 is another story, after giving up on speedfan which gave idle readings of 35/34/-128! I had a look using RealTemp, which is apparently the most accurate way. Realtemp shows my E8400 idling around 35C, which is fine. However, when i fully load the cores (Prime95) the temps rocket up to 60 VERY quickly and then keep climbing. After about 30 minutes they hit 80 on both cores and I decided to halt prime95. I checked the HSF with my hand, and found that the top of the fins and the heatpipes barely felt warm, whilst the bottom of the fins I could just reach round to touch were very very hot. I am sure that I seated the HSF properly with an extremely thin and even layer of Zalman TIM and it is very tightly screwed in. It previously kept a Celeron 352 that was oc'd to 4GHz under 60c. Obviously something is amiss, is Realtemp overestimating? Is my cooler rubbish/broken? Any thoughts?
You may already have tried, but I'd be tempted to remove the heatsink, clean off the thermal paste from both the CPU and heatsink, and start again by re-applying thermal paste and re-mounting the heatsink and fan. I found that when I first built my PC, the idle temp was 70, which was caused because I had not fitted the heatsink properly! It looked ok, but when I tried again, the idle went down to around 35.
