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The fan on the board (and the processor) sometimes decides to go nuts and works on max power. I look in the Task manager and there is no process that loads the CPU, HDD or the memory. The fan is clean (I checked and cleaned again, even though there was nothing to clean).

It just goes crazy, whenever it decides, and keeps the temp of the 2 CPU cores 30 - 45 degrees. And just goes down and up on the power of work, then on max for some time, then up-down and max again and so on.

Any ideas what might be the problem and how to solve it ? Just the constant sound is really annoying when I am working.

P.S. since there's no tag for the models, the laptop is ProBook 4520s. I bought it 2 years ago and have never had hardware problems with it.

EDIT: Forgot to say that I've changed the thermal paste just couple or 3 months ago.

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maybe you can set the power scheme to only go off when it reaches 50 or so. "change advanced power settings" in windows 7. but if there isn't much load on the cpu, that might not help. you could see if speedfan can control it. this is where it's good to have a 7 day no questions asked returns policy.. 'cos it's tough to predict this kind of thing.. even tough to predict it within 7 days. you could try contacting hp, and trying trying to go for a very low power cpu next time like 5w-10w maybe – barlop Sep 3 '13 at 10:37
Did you check the thermal grease under the CPU/Chipset heat sink? It could be old and not cooling your chips effectively. I had similar problems with my laptop, I even had crazy stuff like keys on keyboard mixing up, keyboard/touchpad go offline and CPU temperature was not high too! – Ashtray Sep 3 '13 at 10:46
@Alex - I edited my post, saying that I've changed the thermal paste recently. – Milkncookiez Sep 3 '13 at 11:05
Are you saying then that this is only recent and has only happened since you changed the thermal paste? Or are you saying that this happened before the thermal paste change. Either way that's quite a thing to not mention. Basic troubleshooting – barlop Sep 3 '13 at 11:11
It happened once like a year ago and that was all. Then it started happening again only a week ago. And now it's happening quite often. (so after the thermal paste change, but around 3 months after I've changed it.) – Milkncookiez Sep 3 '13 at 11:41

AS you stated everything is normal in task-bar & no CPU load is detected, i am sure the problem you are facing is a hardware problem due to the faulty fan. Operating temperature of 45 to 60 degree Celsius on day to day usage of laptop is pretty normal (excluding gaming & use of video editing softwwares).

I had similar problem with my laptop 6 months ago, exactly like you described, my first reaction was to look for CPU process or services using extra CPU power, but detected nothing everything was normal, but after disassembling the whole laptop i found out, the problem was within the fan unit, To be more specific, the fan was getting friction from its internal component parts, which were making a lot of noise, something you cant see from your naked eyes.

In this case you have 2 options, either you can buy a new fan for your notebook, its relatively cheap part or else like me you can disassemble your laptop, take out the fan assembly and apply very little amount (quarter of a droplet) of grease oil on detachable plastic wind blade assembly.

(Till now everything is running cool and no audible fan noise can be detected on the laptop after this small DIY repair)

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Basically, you're saying that the fan is not running faster, just louder? This is possible, and lubing the fan may work in the sort term (if you can get the lube inside where it needs to be). But usually this means that the bushings are worn out and the will fan need replacement in the not too distant future. (It's also possible that the fan, or simply the wire feeding the fan, is somehow rattling against something.) – Daniel R Hicks Sep 3 '13 at 16:51
Yes you got the point but Oiling the fan is not a short term solution, it is the only required solution, because every mechanical part in the world needs oiling after a specific period of time & no "bushings" as u said on laptop fan do not worn out, they are designed to have a very long life, they can work for more than 10 years without a problem, but it needs regular cleaning n oiling after every 3 to 4 years depending upon the dust n type of environment you operate the machine in. – DragonFire111 Sep 4 '13 at 4:46
Well, my experience differs from yours, with fans large and small. Journal bearings do wear out, and oiling is not "normal" since most such bearings claim to be "permanently lubricated" (with lubricant embedded in the bearing material) and are not designed to be re-lubricated. Once a bearing begins to chatter it means the fit has become loose (and becomes looser and looser with the chatter) -- oiling will often produce a short-term respite but is nowhere near a permanent solution. Simply disassembling a computer fan to permit oiling (and then reassembling correctly) is a major challenge. – Daniel R Hicks Sep 4 '13 at 11:41
up vote 1 down vote accepted

The cooling plate goes from the CPU, through 1 more component (not sure what, but suppose the GPU) and then finishes at the fan. The thermo paste was ok at the CPU but was kinda' bad and went aside from the other component. I changed the paste on both places and now it runs as charm.

P.S. @DragonFire111, everything was clean and on places, no undesired physical contact of components.

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