Ok good. I think I will keep the PSU, the noise doesn't bother me. I would only change if I was in any danger or if my PC was. This saves me some money. An additional hard drive would be ok? Wouldn't push it overboard?
Oh dear. It seems I am now conflicted on whether to get a new PSU. As one of you claims it is ok and the other indicates a small amount of danger. I might just get a 750w for £59. It would save me upgrading again.
Are you sure that it's the PSU getting loud? The coolers for the GPU/CPU could also be spinning up and making more noise. If you want to verify then, you can open the side of the case and use something to stop the PSU fan. If the noise goes away then it's the PSU...if not then it's one of your other noise makers.
What is the specific model of your beQuiet 530W? The Pure Power BQT L7-530W is made by FSP and the BQT L8-CM-530W is made by HEC. Both PSUs are well-reviewed at techpowerup as good 'value' oriented units.
Every manufacturer does, from time to time, make duds. As Rugger has suggested, determine if the PS is making the noise. If so, it may be time for a new one if it's out of warranty or you cannot wait for a RMA.
If the psu noise is simply from high rpm's, then it is probably operating normally.
If there is a grinding or clicking type noise, then the psu fan might be at fault.
Put your ear cloce to the sound to check it out better.
If you do buy a new psu, only buy a known quality unit.
My current short list of quality brands includes Seasonic, Corsair, PC P&C, Antec and XFX.