Jason wrote:

I'm the OP for this thread. The fan on my ATX PSU seems to slow down at
times and makes a noise so I guess it's approaching the end of its life.

If it's just the fan, you can replace that, Maplins sell case fans for
about a fiver IIRC, you just need to get the right size. I replaced mine
after it started making a continual buzzing sound. The only touble was the
original had been hardwired rather than connected with a plug but I was
able to connect the new one up without much difficulty anyway.