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Author Topic: Overheating laptop  (Read 8818 times)
Ivan
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« on: March 08, 2009, 12:40:59 AM »

My mother is without a laptop due to her hard-drive failure.I'd replace the harddrive, but the rest of the machine is in such a poor state- mainly the screen hinge, which is seized, broken etc. So I am trying to revive an old laptop belonging to wife, which suffered overheating problems, and ran incredibly slowly.

The underside of the rear of the laptop gets too hot to touch after it's been running for 30minutes or more. Here's what I found:

I installed 'speedfan' software. Unfortunately, the computer isn't compatible, so I can't control the fan settings (otherwise I'd just go for an 'always-on' option). But it does give HDD and CPU temperature. The CPU temperature was around 70C even when not running any applications.

I took the various hatches off, and removed the CPU heatsink. It is copper with an aluminium-like sticky pad attached to it. The centre of the pad looked as though it had bubbled, and was certainly far from flat. So I flattened it by poking with my finger. I removed the glue-like heat transfer material that was there originally, and replaced it with some Navitron thermal grease as used in solar panels.

The bulk of the heat seemed to come from the middle of the back of the laptop - and a small heatsink seemed to have 'wandered' off a big SiS chip (whatever that is - graphics and sound?). I reattached using some Navitron thermal grease, but unfortunately, this heatsink is designed to be glued on with the thermal paste, so it's not a perfect solution.

I also removed the battery, so the charging circuit doesn't have any work to do.

NET RESULT: CPU temperature dropped from 70C to 43C, and I've been using the computer for more than an hour, and it hasn't increased beyond 43. The back of the laptop is still hot, but nothing like as hot as before. And, it runs a lot faster - I guess the CPU clock speed is automatically reduced as it overheats to limit the temperature rise.
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Mike N.
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« Reply #1 on: March 08, 2009, 12:59:21 AM »

I am trying to revive an old laptop belonging to wife, which suffered overheating problems, and ran incredibly slowly.

Lots of people have wives like that Grin .

Mike
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rob26440
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« Reply #2 on: March 08, 2009, 01:11:01 AM »

The fan on my laptop sometimes runs at full speed.  Normal if its being hammered.  However, it can also run at full speed continuously when it is just sitting there doing nothing (other than talking to itself and polling around its mates on the LAN).  This means it's bunged up with dust and its time for the vacuum cleaner to come out.  Every aperture gets the full power of the nozzle - no dismantling needed.  Then the fan goes back to normal for a few months.

My son goes one step further - he gives his (work) laptop a blast with the air compressor!  Seems to work but is a bit drastic in my view.
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Rooster
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« Reply #3 on: March 09, 2009, 10:41:46 AM »

My son goes one step further - he gives his (work) laptop a blast with the air compressor!  Seems to work but is a bit drastic in my view.

Using a vacuum cleaner can potentially cause static damage to components. Compressed air (often from a can) is recommended for cleaning inside cases.

Having said that I often use a vacuum cleaner.  surrender
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Roy
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« Reply #4 on: March 09, 2009, 10:45:12 AM »

I took the various hatches off, and removed the CPU heatsink. It is copper with an aluminium-like sticky pad attached to it. The centre of the pad looked as though it had bubbled, and was certainly far from flat. So I flattened it by poking with my finger. I removed the glue-like heat transfer material that was there originally, and replaced it with some Navitron thermal grease as used in solar panels.


AMD once told me that those heat sink pads were meant to be changed annually.

I don't know anyone who does, although as you've discovered after a while they do need doing. Incredible what a difference decent thermal contact makes!
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Roy
alfie
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« Reply #5 on: March 09, 2009, 10:46:02 AM »

Buy her a new one you old cheapskate !
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insolare
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« Reply #6 on: March 09, 2009, 11:00:57 AM »

I always prefer to suck rather than blow!  Grin Blowing dirt away can force it down edge connectors and into pins of plugs. If you are going to blow dust away then do it gently. No 1000 psi airlines!
As for static damage, it's very unlikely to static damage a chip once it's in circuit.
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Justme
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« Reply #7 on: March 09, 2009, 11:34:18 AM »

Its most likely that the battery is duff so the internal regulation is working overtime to try to charge the bat & power the laptop hence all the heat.

Does it get as hot running of the bat?

(edit to add)
Just spotted it does not.

Justme
« Last Edit: March 09, 2009, 11:38:59 AM by Justme » Logged

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RichardKB
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« Reply #8 on: March 09, 2009, 10:21:06 PM »

Most of you probably know that my job is repairing laptops, and dust curtains across the heatsink fins is a common cause of fan running flat out.

I just had a turion laptop that the fins where cleaned of fluff but the unit still kept the fan screaming when the cpu was running intensive science applications. I removed the heatsink thermal pad and applied thermal compound, the fan never goes full speed now even when cpu is maxed out for hours.

Rich
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Taffyboy
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« Reply #9 on: March 10, 2009, 01:14:08 AM »

I find running them in a bucket of water cures all overheating problems...

Of course, said bucket was recycled, and the water was passed, as safe, by me...Copiously..
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sunshinekid
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« Reply #10 on: March 10, 2009, 05:25:48 AM »

On the subjecy of CPU speed vs temperature I was in the local PC repair shop and noticed a large tower case which was open and had a small compressor in it, like the one in a fridge.  The guy explained to me that he was trying to see how fast he could overclock the CPU by cooling it as much as possible!

He'd not finished yet, but he told me he was doing it just for fun. LOL!

Steve
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