Better to replace the lot.
Say if 1000uf one is leaked replace all the 1000uf ones. Just a precaution.
Cause the 1000uf ones will have come from the same batch when assembled u know.
so even if the rest 1000uf ones OK, it won't be after a while
That's what I do.

I have a few 2200uf 10v caps spare. Would these do to replace the 1000uf 10v caps on the PSU? The two that look a little suspicious are interestingly the ones going from the 12v rail to ground, so I'm hopeful that this will fix the issue.

 

Will like work just fine.

 

I have a few 2200uf 10v caps spare. Would these do to replace the 1000uf 10v caps on the PSU? The two that look a little suspicious are interestingly the ones going from the 12v rail to ground, so I'm hopeful that this will fix the issue.

Just curious? 10v caps across a 12v rail? Wouldn't that call for 25v caps? I may be wrong…

 

That 450W rating is for all the voltages the supply creates combined. The 12 volt portion may only be capable of outputing a small fraction of the full 450 watt supply rating.

Look closely at the supply or find its spec sheet and look for the amps that 12 volt section is rated for.

 

What you are hearing is a sub-harmonic of the power supply switching frequency. The main switching freq is ultrasonic, but it can induce physical vibrations in the transformer windings and in the core. That it varies with load confirms this.

Other than glopping everything with RTV, I know of no fix.

ak

 

Just curious? 10v caps across a 12v rail? Wouldn't that call for 25v caps? I may be wrong…

Yes, my mistake. Across the 5v and 3v rails they're 10v, but for the 12v rail they're actually 16v. They were a bit hard to access so instead I ADDED some similar caps (16v 2200uf) to the 12v rail's output wires (basically the wires that go to the graphics card). Unfortunately there was no change, and it sounds just as bad as before.

Unless I have to remove the faulty caps (if they are faulty; they don't show signs of damage as that 'leak' I suspected was only dust) for it to have an affect?

Regardless, I'm pretty sure the PSU never used to make this noise a year or two ago. Are there any other components that can degrade, causing this sound, other than the caps?

That 450W rating is for all the voltages the supply creates combined. The 12 volt portion may only be capable of outputing a small fraction of the full 450 watt supply rating.

Look closely at the supply or find its spec sheet and look for the amps that 12 volt section is rated for.

The 12v rail is rated for 33A, so just shy of 400w capability on 12v alone.

 

...
Regardless, I'm pretty sure the PSU never used to make this noise a year or two ago. Are there any other components that can degrade, causing this sound, other than the caps?
...

Caps on the video card!

I already said that.

My video card here has some new electros soldered to the back of it, the caps went bad a while back. Then the video card draws high current pulses that de-stabilise the main PSU.

 

Thanks for that. I don't have an ESR meter, so what I might try is replacing those capacitors if I have some equivalents spare and seeing if anything improves.

Thanks for your help so far Bertus.

There are some tricks of the trade you can use without an ESR meter, very bad capacitors will be bulged on top, failing caps will get hot in normal running - you can feel the temperature of the secondary side caps with your finger, but the aluminium can on the primary side caps are likely to be live!

For replacements; you can't use just any old electrolytics from the junk box - you need very low ESR types designed for PSU applications.