PC cool and quiet with low loads, but CPU overheats at load

[theycallmebruce]

So, I've assembled my system, and after some trial and error I have the following configuration:

- Antec Three Hundred case
- Vent in side panel blocked
- Rear 120mm Tri-Cool replaced with 120mm Scythe S-Flex 1500 RPM, controlled by system fan header
- Top 140 mm Tri-Cool set to Low
- Front 120mm Scythe S-Flex 1500 RPM, manually dialled down to about 700 RPM
- Athlon 4800+ (Brisbane core) with Scythe Ninja Mini; 120mm Scythe S-Flex blowing backwards through heatsink, controlled by CPU fan header
- Seasonic S12 430W PSU
- Gigabyte MA78GM-S2H motherboard
- Sapphire Radeon 3850 Ultimate (the fanless one with the enormous factory cooler)

Now, all is well and good when the system is idling or I'm just browsing the web or similar. The CPU and rear exhaust fans spin down to about 900 RPM each. Despite having five fans, the system is quiet enough for my liking as they are all spinning slowly. The CPU, GPU, motherboard and hard disk all stay nice and cool.

However, when I fire up Left 4 Dead, the CPU starts heating up pretty quick. The CPU fan spins up to 1500RPM (which is fine, that's what I want), but still its temperature keeps inching its way up that familiar exponential curve until it gets close to 100 degrees Celsius and I have to quit the game. It might take an hour of play to get that hot. The other components all heat up a bit but stay at fairly sensible temperatures. The rear exhaust fan stays at 900 RPM because the motherboard temperature is not really rising at all.

So, my question: based on your experiences, what is the most likely culprit causing the CPU to get hot, and how can I verify it experimentally?

[~El~Jefe~]

get arctic's Ceramique, and their cleaner kit.

re-apply heatsink is only way to know.

ceramique is flawless.

also note: not many games use both cores like l4dead does

[MikeC]

Could be bad interface, could be the mini ninja is just not effective enough cooler, you need a bigger one. I'd have gone for a 120mm fan heatsink -- maybe a xigmatek or thermalright hr01.

I wonder if you've identified the CPU correctly tho. Hard to imagine any system would keep running at 100C CPU temp.

[baconandeggs]

firstly what program are you using to monitor the temps, some CPU temps are reported incorrectly due to sensor or program issues. btw what are idle temps?

check if the minja is seated properly and conducting the heat from the cpu by just touching the top of the minja, does it reflect what 100C conducted through the cpu cooler would feel like? (im not sure but at a guess like touching the outside of a cup containing boiling water ??? dont quote me on this).

[edh]

I wonder if you've identified the CPU correctly tho. Hard to imagine any system would keep running at 100C CPU temp.

Having had a Google, there seems like a history of these issues. AMD puts the max temp at 55-72C:
http://products.amd.com/en-us/DesktopCP ... &f10=&f11=

[theycallmebruce]

Well, after a dramatic day, things are better. Short version: You guys were right. I installed an HR-01, CPU now stabilizes around 60 deg C on long sessions of Left4Dead. Idle temperatures and fan RPM also lower. Thanks for the help! The temperatures I'm quoting are using Everest ultimate edition. I thought 100 sounded pretty hot too, but that's what it was saying.

Longer version:

I removed the Ninja Mini, stole the Thermalright HR-01 from my old machine, cleaned up all surfaces with medical swabs, and applied plenty of Thermalright paste (think I might not have put enough last time). Thought I was all good to go, using the AM2 mounting kit for the first time on my HR-01 (previously mounted on 775 CPU).

Then.. turns out the HR-01 AM2 mounting kit relies on the stock retention mechanism on your mobo having threaded holes that poke up. Mine didn't. So after a bit of swearing and two trips to the local hardware store I put together my own "bolt through kit" - just four bolts, nuts and some spring washers. NOTE: if anybody else needs to do this, you want 4x M5 25mm bolts, and corresponding 4x 5mm nuts and 8x spring washers. You have to put the washers on top of the mobo and bolt up from underneath due to the length of the bolts. If you can find 20mm bolts they might go the other way but I couldn't find them.

Just made it out of the hardware store before closing time. Realised that the whole day, including a fair bit of cycling around in our unseasonally hot 35 degree Easter weekend, I hadn't eaten or drunk anything and I had a mild headache.. CPU not the only thing overheating! So I went and ate a big dinner.

Cycled home at high speed. Bolted the heatsink on and reinstalled the mobo in the case. Powered on and.. uh oh. No POST. Did I screw that thing down too tight and crush my CPU??!!

Suddenly felt really sick, hot, and faint .. all the rushing around and not enough water. Managed to stumble to bed and slept for a couple of hours.

Woke up feeling a lot better. Drank a litre of water. Went back to look at my machine and.. I had forgotten to plug the P4 power connector back onto the mobo!!!

Anyway, just had a one hour session of L4D and all seems good now. Graphics card getting a bit hotter than before, stabilising around 60 or 70, but that doesn't worry me. I put it down to the fact that I had to mount the CPU fan blowing air vertically up due to the orientation of the heatsink constrained by the mounting holes, so the graphics card is getting less spillover cooling from the CPU fan now.

Have to say, I really don't like that "clip down" heatsink retention mechanism used on AM2 processors.. I've always had Intels before and I didn't like the push pins much but they beat those damn clips.