Re: beeping and powering off from overheating>?
Your system was obviously loaded up with dust and debris slowing fans down and you may have seen the fan blades themselves with a coat of dust all over those. Some believe it or not use old nylons for wiping the dust off of those on the larger case fans seen on newer builds.
Dust is the worst offender for temps on any system. Yet the older Atholons saw a max temp of 90C on most with the 3200+ being 85C for that and a few others. 54C is seen mainly when seeing a good load or ocing an older cpu with the stock HSF used and not a better 3rd party cooler.
Buy a few cans of compressed air since that is preferred over a vacuum cleaner plus for being onhand for blowing buildup out on some type of regular basis. An overheating supply can see problems as well as anything on the board itself. A hot supply also adds heat inside a case effecting over things.