Prob with old computer. Crackles like a geiger counter. Any ideas?

Hi everyone.
My dad's 6 year old computer has recently started playing up. It keeps restarting when it tries to load up, and even when it successfully loads windows, doesn't last long before it restarts. It will then stop loading windows at all, and stop sending a signla to the monitor (either that or the monitor turns itself off due to their not being any signal going to it). The internal speaker then starts crackling every so often like a geiger counter and continues to restart. I've replaced the motherboard with the same model, but with no success.
Before I look up all the components and list them in detail, doea anyone know what the problem might be?
Any suggestions would be great.

Could be many things.

If it's six years old - has it perhaps got clogged up with fluff (the physical not software kind!) would be worth checking all fans / filters / airways.

it is also worth checking everything is seated properly - Maplin sell electrolube - or similar which will clean connection.

Inspect the cables from PSU (to everywhere) for damage / breaks / nicks / meltdown etc.

I wouldn't be surprised if the pc speaker cable being shorted couldn't cause strange behaviour (and crackles). It is connected into Mobo

I have had several PSU failures with old machines - PC world have been quite decent about sale or return and a local shop may also be.

If you have a pci sound card fitted and it's near the processor try moving it to a further away slot as the card can pick up interference from the cpu, if the m/board has built in sound then sorry dont know what to suggest.

Hi everyone.
I have had no internet connection today. I've been on the phone to Pipex all day, who said that their end of the line is fine. After trying to sort it out all day, I gave up and switched my dad's old computer off (the one with the problems). Hey presto! Internet again. I switched the computer on again, and just before it beeped at the beginning of the load-up process, the internet went off again. I turned the computer off again, and the internet magically reconnected again!
My dad's computer isn't even connected to a phone line or to the broadband router, but it's managing to stop the router connecting to the internet when it's turned on!
Does anyone know how it might be doing this?

Ya , suspect your dad,s computer is putting out a 'spurious frequency' which will be killing the broadband connection. Could be coming from any part of old machine but possible be due to monitor, psu , graphics card etc . Try moving old comp to a different room but I suspect that this may not solve prob as 'spurious' can kill bb from afar. BB can be very sensitive at times .

I replaced my dad's old psu with my brother's comp's psu, and that was what was causing the router to disconnect. I know this, as I put it back in my brother's comp, turned it on and had the same problem. So now I have to buy 2 psu's, one for each computer! lol
At least it won't be too expensive ;)

Your lucky , it could have been a 'spurious ' from half a mile a way almost impossible to find without 'specialist equipment' . Lots of guys out there are getting cut-off on bb at 1600 when the kids come out of school . :):). Power to broadband :):) it's great.

haha, yeah I know what you mean. It doesn't help that we're at the end of the exchange either. The broadband is a bit breathless when it reaches us shall we say!
It doesn't help that it's being squeezed along telephone lines that have seen better days! I'm thinking they're still the lines that were there before the war hehe

Heard about this guy that got bb the other day :):). He was 85 metres from exch .:rolleyes: What a 'lucky chap eh !":):) Glad ye got yer thingie sorted .