I have a machine I just built for a family member with a Gigabyte ED45-UD3P mainboard and Intel Core2 Quad Q9400 processor. I've been testing it a bit with Prime95 and Core Temp before turning it over and am getting some seriously funky results.
Idle temps for all four cores fun at 33-35ish C and this stays constant regardless of how long the thing is left on. Under full load, though (using any of P95's torture tests), things get real interesting. Within the first minute or two, I'm well into the 60-70 degree range and beyond that it's 80's-90's until it levels off in mid to upper 90's and stays there until I shut P95 off. And, by this point, I'm shutting it off pretty darn quick. After that, temps pretty well plummet back into the idle range in about the same amount of time it took them to climb, with that initial drop being very noticeable. And there you have it: my issue.
Also, just to clarify, thermal protection/monitoring *is* enabled in CMOS and the machine does not shut down or change in any visible way other than the CPU fan doing a bit more whirring. (And it is whirring, btw...although much more quietly than what I'm used to hearing.)
I haven't done a lot, but I *have* installed CPU's before without issue - and this one's got me stumped. And I'm not sure where to go from here, but these are my prime suspects:
1. Thermal Paste: I ran a thin, horizontal line of Arctic 5 over the CPU as prescribed on their website. Didn't go crazy but, if anything, I used a little too much rather than a little too little. I doubt this is my issue.
2. Fan/Heatsink Installation: This is mainly what I'm wondering about. Fan and sink are in place and seated firmly, but only after a small wrestling match that went down before me finally getting it right with pressure on opposite, diagonal corners rather than doing it one whole side at a time. During said wrestling match, the fan had to be removed and re-seated a few different times. All this happened within a couple minutes of applying thermal paste in the first place and I don't think it changed all that much other than squishing the paste a little more than normal. That said, it's on my mind so I'm mentioning it.
3. Inadequate Sink/Fan Not a likely contender but, again, just putting it out there. The fan I'm using is the stock Intel fan that shipped with the (socket 775) processor.
That's about all I can think of, and I'm not about to turn this thing over without knowing it can beat the heat. If anyone has any thoughts or suggestions that might be of help, they'd be most apprec...
If memory serves, Artic Silver needs some time to acieve maximum results. I might be wrong but without checking I think it's something like 200 hours of operation.
Your idle temps are okay. Under load you probably should be somewhere in the 50 to 65 degree range. It's been some time but I seem to recall a few threads here about strange results with Core Temp. I think it had to do with different versions of the utility and different drivers.
What pc case do you have? How is the ventilation and air flow?