Computer Randomly freezes

[Mark342]

Recently one of my PC's has been having a bit of trouble.
It sometimes freezes and you hear the "capacitor noise" before it eventually comes back.
This happens when PCLinuxOS is up and running, during GRUB boot up, and when the BIOS screen appeared.
I have tried removing the dedicated GFX card in favor of the integrated one to reduce power consumption , but it still happens.
My guess is there is a problem with the power supply or capacitors, but this machine is only about 3 years old.
Does anyone have an idea of what the problem may be?

Of note: When the desktop is up it usually only freezes when CPU usage is high.

[djohnston]

First try running Memtest from a live CD to eliminate the possibility you have some bad RAM. If you're confident that RAM isn't the problem, shut the computer down, take the case lid off, and inspect the motherboard for any bulging capacitors. It very well could be your power supply. How many watts is the power supply rated for? And how many drives, or anything else that is consuming power, do you have attached? Is the AC line filtered from power spikes and surges?

[bicol_willem]

"Of note: When the desktop is up it usually only freezes when CPU usage is high"

This could point to "bad cooling". Is the heatsink properly attached? Is the heatsink fan running well?  Is the heatsink dirty maybe?

[Yoyo]

This one's easy. It's either a cooling problem, bad ram (physical or overclocking problem), or too much hardware for a cheap underpowered power supply.

[T6]

or all the previous, you are not giving any specific details like psu power, ram type and amount, cpu type and speed, mainboard type and date to determine if the system is using too much a possible bad psu and if you have done any maintenance to the machine, basic clean

"It sometimes freezes and you hear the "capacitor noise""

like BANG!!!!  ?   

btw, what kernel are you using?

[genomega]

Take a look at your system log and look for cpu messages.

[j-retired]

What EXACTLY is the "capacitor type" NOISE? 
Are you still running a CRT monitor?
With some CRT monitors, if the display goes blank, the EHT supply rises due to reduced load, and falls when the load (ie, a picture) reappears. 
This often produces static discharges on and around the screen area, and internally around the tube anode connection, which produces a nice threatening crackling sound!
 I'm not suggesting this is a cause, just that it may be sending you off on a wild goose chase.
j