Overheating CPU that idles at normal temps.

[Accessless]

A Little while ago I replaced my stock CPU cooler with the Corsair H60 Liquid cooler. Things went well, load noise went way down and tempuratures followed suit. However all of a sudden I'm encountering over heating problems from as little as 25% CPU load. What's even stranger is that my idle temps are perfect. Currently sitting at 35°C (95°F).
When I replaced the cooler I used new Thermal compound (didn't realise at the time that the H60 came with one of those thermal pads).

So to some up:

- High load temps but low idle temps
- New Thermal grease
- Little dust build up

Please no one suggest knackered thermal sensor on CPU.

(It's my profile computer btw)

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[Calum]

The fact that the temperature spikes up quit quickly, rather than taking some time to heat up, suggests to me that either the cooler isn't making proper contact or that the pump isn't working as it should - as opposed to the cooler being unable to deal with the heat output and getting saturated.
First thing I'd check is the pump, how is it currently connected?  if it's on a motherboard header, try it on a Molex to 3 pin fan adapter if possible, just to rule out either the header or the board doing something funny with voltage/speed control.
If it does the same thing directly connected to the PSU, is the pump vibrating, making any odd noises, or is it totally silent?  There should be a slight hum, a bubbling noise or anything odd could indicate a trapped air bubble, whereas total silence might mean it's not functioning.
Is the radiator getting warm at all, or staying stone cold?  That could also indicate an air lock or lack of heat transfer.
Finally it's worth removing the cooler just to make absolutely sure it's seated properly, you should have a good spread of thermal paste and indication that it's contacting across the whole base, not, say, skewed to one side.  This is quite unlikely if it was working fine before and if the PC hasn't had any knocks or bangs to unseat the cooler, but it's worth checking as a last effort anyway.

[Accessless]

First thing I'd check is the pump, how is it currently connected?  if it's on a motherboard header, try it on a Molex to 3 pin fan adapter if possible, just to rule out either the header or the board doing something funny with voltage/speed control.

I could try that but my experience with older motherboards tells me that the BIOS will not POST if a CPU fan is not detected. Haven't put it to the test recently though. Also speed fan & SIW report good RPMs from the pump and fan.

If it does the same thing directly connected to the PSU, is the pump vibrating, making any odd noises, or is it totally silent?  There should be a slight hum, a bubbling noise or anything odd could indicate a trapped air bubble, whereas total silence might mean it's not functioning.

I have never known the pump makes any noise, but if it were not functioning at all then the surely the CPU would overheat very quickly at idle speeds. I'll give it a bit more attention though.

Is the radiator getting warm at all, or staying stone cold?  That could also indicate an air lock or lack of heat transfer.
Finally it's worth removing the cooler just to make absolutely sure it's seated properly, you should have a good spread of thermal paste and indication that it's contacting across the whole base, not, say, skewed to one side.  This is quite unlikely if it was working fine before and if the PC hasn't had any knocks or bangs to unseat the cooler, but it's worth checking as a last effort anyway.

As it turned out there was a build up of dust between the radiator and the fan (not visible until dismantled), but this has only improved the situation. I had to stop a Prime95 stress test after reaching 75°C (167°F). I'm sure when the water cooling was originally installed the tempuratures did not exceed 65°C (149°F). Anyway I will be checking the pump mounting later. I will keep you apprised.


After taking the time to convert all my temperatures to imperial I realised that you (Calum) are also from the UK England/Scotland/Wales/Ireland

[Calum]

I could try that but my experience with older motherboards tells me that the BIOS will not POST if a CPU fan is not detected. Haven't put it to the test recently though. Also speed fan & SIW report good RPMs from the pump and fan.

With all-in-one coolers, the fan should be connected to the CPU fan header, the pump should be connected onto a different header - one that is not throttled or speed controlled.  So, even if your board does freak out if no CPU fan is detected (this can usually be continued past or the warning can be disabled anyway on modern boards), it won't matter, because your fan should be on the CPU fan header anyway, it's just the pump I'm suggesting to move elsewhere.  It's good that the RPM is being reported as expected but I think it's still worth a try connecting it to the PSU instead of the board if possible, just to rule it out.

I have never known the pump makes any noise, but if it were not functioning at all then the surely the CPU would overheat very quickly at idle speeds. I'll give it a bit more attention though.

I also think it's unlikely that the pump is totally dead, but it's possible it's not functioning properly, such that it is flowing less than it should do.  This would cope OK at low loads but the temperature would quickly spike under load.  The pump shouldn't be loud but you should be able to just about hear and feel it working if it's operating normally.

As it turned out there was a build up of dust between the radiator and the fan (not visible until dismantled), but this has only improved the situation. I had to stop a Prime95 stress test after reaching 75°C (167°F). I'm sure when the water cooling was originally installed the tempuratures did not exceed 65°C (149°F). Anyway I will be checking the pump mounting later. I will keep you apprised.

That does still seem too high, yes.  It's worth checking if the radiator is getting warm, hot, or staying cold when the CPU's under load - I'd expect it to be warm.  Too hot means your fan isn't dissipating the heat, whereas cold means there's some kind of flow problem and the heat isn't reaching the radiator to be dissipated.

After taking the time to convert all my temperatures to imperial I realised that you (Calum) are also from the UK England/Scotland/Wales/Ireland

Heh, I certainly am!

For what it's worth I've had quite a bit of experience with these all in one coolers and ran into most of the issues that one could expect to encounter - airlocks, faulty pumps, leaks, and times when they're just not up to the job.  For it to have been working and cooling pretty well, then stop doing so well, suggests to me that something has gone wrong - I don't mean that to sound so basic, but what I mean is that something has changed, rather than something being wrong from the start.

[Accessless]

Checked pump/heatsink mounting today (sorry about the delay, time has not been allowing recently). I replaced the thermal paste and have yet again seen only minute improvments (now takes a few seconds longer to cook).

As I havn't seen any worring readings I'm going to assume that fan/pump throttling is not an issue. I still have no idea if the pump is actually functioning for all I know the blades could have fallen off the impeller and it would still state good rpms.

I can feel heat through the pipes and in the reservoir/sump but the radiator feels quite cold although I havn't sustained any high tempuratures for any length of time. How would a air bubble or lock present itself? And can you bleed it?



This seems to be going more into mechanics now, maybe there should be a new forum category?

[Calum]

Checked pump/heatsink mounting today (sorry about the delay, time has not been allowing recently). I replaced the thermal paste and have yet again seen only minute improvments (now takes a few seconds longer to cook).

What did the spread of paste look like, did it look like it was making good, even contact across a good patch of the CPU?

I can feel heat through the pipes and in the reservoir/sump but the radiator feels quite cold although I havn't sustained any high tempuratures for any length of time. How would a air bubble or lock present itself? And can you bleed it?

Normally an air lock would present itself as either a noise, if present in the block/pump, or as a cold or hot area of the radiator, or just high temperatures if there was an airlock in one of the coolant pipes slowing down the flow.  If the radiator is quite cool, perhaps close to ambient temperature, I wouldn't be surprised if an airlock was to blame, especially if the block and pipes are warm this would suggest reduced flow or an airlock.  Try turning the machine off and tilting it to each side and then upside down - sounds odd but it often helps.  Try it with the machine running if that makes no difference, although of course this is trickier and I would at least advise unplugging any mechanical drives to avoid any possibility of damage.  The above has helped dislodge air bubbles and air locks previously for me, generally in proper water cooling setups although I also have seen it do some good in sealed systems like the H60 back when I used to build systems at work with those in.

[Accessless]

Ok I'm about ready to ditch this thing. Apart from powering the pump independatly whilst holding it up to my ear to listen for functionality I've tried everything. I enjoyed my water cooling for all of the 5 months that it lasted but now I'm losing I have lost my patients. I would return it but I don't want another one, I could return it and sell the replacement on ebay though thinking about it.

Any recomendations on an air cooling system that doesn't make my PC sound like a vacuum cleaner?

What did the spread of paste look like, did it look like it was making good, even contact across a good patch of the CPU?

Old thermal paste was a little dry, new paste was thinly (but adequately) applied across the whole CPU.

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[Calum]

It's definitely worth returning it as Corsair's service is generally excellent, however I'm unsure where you'll have to ship to these days (assuming the retailer won't handle the return, but do try that first) as I heard somewhere they now make you ship returned items to Holland.  Still, even shipping to Holland would cost less than you'd make by selling the RMA replacement, so it's worthwhile.

If you'd asked me that question but a week ago I would've send you a spare cooler for free as I had two Thermalright Ultra Extremes sitting around, but they've now been sold - not the newest cooler but very good nonetheless.
As for recommendations, it depends what you're after (cooling capability and your budget) but if you have enough room in your case, the Deepcool Lucifer seems excellent value for a higher-end cooler and should be pretty quiet too.

I can sympathise with your frustrations as I have never been a fan (pun not intended) of closed loop liquid cooling.  More expensive and less capable than air cooling, with the potential for pumps to die, air locks or leaks to develop etc.  "Proper" watercooling does cost more but is much more flexible, performs far better (can be optimised for performance, silence, or any blend of the two...both if you like) and is more extensible, therefore a moderate investment can actually work out fairly reasonable in the long run.  So, I've never seen the point in the closed loop coolers although they are wildly popular so it seems most disagree.

[Accessless]

Thought that I would finally update this thread with a big green tick.

Bought a 'be quite! Shadow Rock 2' Air cooler. It may be the size of my head but it maintains the same temps as the liquid cooling (functioning properly) & as a bonus is actually quiter.


So learn from my folly. Do not be fooled by the liquid cooling fad, stick to what we know is best. Air... It helps you live!

[Calum]

Glad to hear you got things straightened out, the Shadow Rock 2 is a great cooler.  I completely agree, good air cooling beats closed loop coolers any day.

[DaveLembke]

Good to hear you solved the issue and thanks for the laugh with:

stick to what we know is best. Air... It helps you live!