OK, guys, got a technical-type question for you:

I bought my sister a new laptop, and she gave me her old Dell Latitude c640 that had been crapping out (freezing, crashing, etc).

I thought it was an overheat problem -- I installed the i8kfangui220 fan utility.  The computer seemed to crap out when the processor hit 50C.  So I set the fans running 100% 24/7, which works until you try to do a task (e.g. defrag) -- the temp gets up to 50C+ pretty quickly despite the fan.

So I thought problem solved, I'll just find a way to cool the laptop externally.  Voila!  I put it on top of a fan

So that kept the CPU, GPU, and HD <40C, but the m*****f***** still freezes up.  The longest I've been able to keep it running is 5 minutes.

I've switched out the RAM and HD, did a clean install of winxp, reseated the heat sink with new thermal compound -- no difference.

So what do you guys think?  Bad processor?  Bad mobo?

I don't have much experience troubleshooting laptops, but I'm willing to destroy this laptop in order to learn

Start with the easy testing.  Google the "Ultimate Boot CD" and burn a copy of it.  When you boot the laptop off of the CD run the memory test utilities and the drive tests.

Start with the easiest, cheapest parts first.

if you  have done a fresh install of windows.   all that is left is hardware.    probably the board is bad, if you have switched out what you said

Quoted: OK, guys, got a technical-type question for you: I bought my sister a new laptop, and she gave me her old Dell Latitude c640 that had been crapping out (freezing, crashing, etc). I thought it was an overheat problem -- I installed the i8kfangui220 fan utility.  The computer seemed to crap out when the processor hit 50C.  So I set the fans running 100% 24/7, which works until you try to do a task (e.g. defrag) -- the temp gets up to 50C+ pretty quickly despite the fan. So I thought problem solved, I'll just find a way to cool the laptop externally.  Voila!  I put it on top of a fan So that kept the CPU, GPU, and HD <40C, but the m*****f***** still freezes up.  The longest I've been able to keep it running is 5 minutes. I've switched out the RAM and HD, did a clean install of winxp, reseated the heat sink with new thermal compound -- no difference. So what do you guys think?  Bad processor?  Bad mobo? I don't have much experience troubleshooting laptops, but I'm willing to destroy this laptop in order to learn

FYI -- Lots of Dell machines were effected by bad capacitors that can sometimes manifest as heat problems. Do some searches on Dell Capacitor Problem and see if that computer is one of the effected ones.

If so, the computer is practically worthless.

I have right here a Dell Lattitude C600 with the same soorts of problems (runs too hot, freezes, reboots, etc.).  Have also tried reinstalling the OS.  It will boot the ultimate boot CD but it won't run the programs.  My guess is my motherboard is fried but I may try swapping the memory.

And they wonder why I tell people to buy Thinkpads.

GunLvr

With laptops, it could also be a bad battery.
~

alot of laptops that power off due to over heating:   I have been told to tell customers to buy a laptop stand

something that will lift the laptop off the ground just enough for it to get better air circulation.   I thought they were full of sh**  but we lifted different laptops having the same issue, and they didn't power off after that.  

Dells overheating is a known issue, a design flaw. Dust collects on the heatsinks and in the vent areas, trapping heat. Get yourself an air compressor and blow out your vents. There's probably a shitload of dust on your heatsink, too. Pop the keyboard off and take a look. Seriously.


edit: cruze5's suggestion of a cooling stand is also a good idea, I use one, and blow out my vents regularly, no problems here. Had this dell laptop I'm using right now for almost 3 years.

Quoted: Dells overheating is a known issue, a design flaw. Dust collects on the heatsinks and in the vent areas, trapping heat. Get yourself an air compressor and blow out your vents. There's probably a shitload of dust on your heatsink, too. Pop the keyboard off and take a look. Seriously.

you forgot to tell them to install linux       that will fix everything else

Quoted: Quoted: Dells overheating is a known issue, a design flaw. Dust collects on the heatsinks and in the vent areas, trapping heat. Get yourself an air compressor and blow out your vents. There's probably a shitload of dust on your heatsink, too. Pop the keyboard off and take a look. Seriously. you forgot to tell them to install linux       that will fix everything else

He wasnt complaining about windows, so I let him slide this time.

Thanks for the advice, guys.  I've cleaned all the dust out of it, tried the cooling pad (something even better than a heat pad -- 9 inch turbo fan).

I think the mobo or the processor is fried.  I'll have to see if I can find either one cheap on ebay.

I seem to have fixed my dying Lattitude C600 by removing one of the memory sims.  The thing seems to run just as it should now.