Desktop Problems & Laptop Problems (below)
The Most common things that kill your computer is Heat, Dust, and Smoke.
And when these 3 get together, your systems going down!(eventually)
Click on any photo for the larger view

Dust can kill your computer by impeding the cooling process, causing heat buildup.

You should be able to see the cooling fins under the fan instead of that pad of felt. Fins in next pic

Here you can see the fins but the clump of dog hair stopped the fan.

Same fan 2 months after cleaning

My Number 1 Tip: Get Your Computer Off The Floor!!!!

Try to blow out your system at least once a year, or have it done for you. A Vacuum just doesn't work. I personaly blow out my system every 6 months.

Smoking Near your computer can also hurt the cooling process, Plus it's Gross!

This is from a heavy smoker

Smoke causes things to stick together.

I think i just threw up a little.

When the Heat increases, Internal parts begin to fail,
these are Pics of the capacitors bulging, cracking and leaking.

When the capicitors get hot

They burst and leak causing shorts

The right 1 is starting to bulge

Laptops Major Killer is heat at the DC jack connector.
These pics are from a Toshiba Laptop where the connector area has melted the solder spots, you can actually see the metal has seperated from the post. you can also see the different colored and warped plastic around the area.

These Photos are from the same Toshiba Laptop as above.
During the repairs i noticed the pad on the cooling fins, then i realized it was dust piled up over the years.

Different Laptop
Same Problem.