|"...stopped booting up. The monitor dosen't come on, & it continuously gives out long beeps.I understand this usually means a memory problem (RAM)" |
No, it usually doesn't - a long beep is often either a video problem, or your mboard bios is set up to warn you if the cpu fan stops or runs too slow, or the cpu is too hot, or some voltage is too far out of whack.
"I have changed these around & even put a friend's ram in but still no difference.'
Mboard ram compatibilty varies a great deal, apparently especially when it is DDR ram - ram working in your friend's mboard doesn't necessarily mean it will work in your old mboard, or your new mboard.
You can look up what ram will work in your mboard for sure at many large memory module manufacturer's and memory distributor's web sites.
Ram doesn't suddenly go bad, especially if there was more than one module, unless something has damaged it - there may be nothing wrong with it.
Since you have eliminated the possibility of the video and the mboard, either your cpu is damaged or fried, or your power supply is defective (which may have damaged or fried your cpu).
"The cpu dosen't look burnt or damaged at all, & I understand that I would get high/low beeps if that was the problem."
When we say a cpu is fried, it doesn't necessarily mean that literally - it just means it no longer works.
The cpu doesn't have to look burnt, and it often doesn't - if it's core voltage got too high, it can "burn up" inside like a fuse does, without overheating.
What beeps you get varies a great deal, if you get any at all.
Power supplies can go out of whack intermittantly - the only way to check for that is to have monitoring software running in Windows all the time. Try another known good power supply - if it still doesn't boot the cpu is fried - if it boots, your power supply is defective.
This can happen to any power supply - it's jusy a lot less likely with a better one.