Acer 7720g stopped posting

My Acer laptop is fairly old now; I've had it since ~2008 and it's worked fine since then. I've had the occasional hang in the past year or so which I've put down to overheating problems. The fan has been a bit noisy.

Tonight it crashed while I was browsing the internet and I decided I'd clean the fan to try to stop it happening so regularly. The mouse cursor wouldn't move and the num lock button did nothing, so I had to hold the power button. Once it was off, I removed the battery and took the four screws off the back and saw the metal grill next to the fan had a thin layer of dust over it, so I removed the dust with a screwdriver and put it back together.

After this, the laptop wouldn't post.

I've tried using an external monitor, which does nothing. I've tried removing all power for half hour. I've tried holding the power button for a minute with all power removed. I've tried powering using AC only, battery only, both, I reseated the memory and nothing seems to make any difference.

The laptop powers up but the screen stays off. The fan spins for 2-3 seconds then it switches off. After another 15 seconds or so the fan comes back on. Num lock/caps lock etc. does nothing. There are no beeps or any clues as to what might be wrong.

I thought it might be graphics card related but typing my BIOS password and pressing enter does nothing.

I can't think of anything that I may have done to damage it.

Any suggestions?

 

ok, common routine check. Does your laptop have 2 memory bars? if so take one out and turn the system on if fails than take it out and put another one in if fail too then your memory sticks went bad, to be sure, check the memory bars on a working laptop. other things to check, if the cpu died. do you have another cpu? that fit that laptop? I read the services manual this laptop use Intel and I know similar looking laptop use Amd( http://global-download.acer.com/GDF...ep3=ASPIRE 7720G&OS=ALL&LC=en&BC=ACER&SC=PA_7). If the system is not posting is because either cpu when bad or the memory, or shorted on the internal PS regulator but not likely but possible.

 

It could still be the video card. It's a common misconception that a failed video card always results in booting behind a black screen - it can easily cause lockups as well (see plugging in an unmodded 9600M GT in an unpatched 5920G).

 

It has two sticks, and I've tried both/each one/none in various combinations and the symptoms have not changed.

I do not have another CPU to test.

Should the system do anything (e.g. beep) when the video card has failed? Also, I did not experience any of the symptoms of a dying card at any time during its life.

 

I guess you still have the original GeForce 8-series card in the machine.

GeForce 8 cards usually fail without any warning signs, due to Bumpgate. Usually, there is no beeping either, the screen just stays dark, and often booting is prevented.

A good way to test this is to try to boot with the MXM card removed. If Windows does boot without a card, then the card is dead.