Hey guys it's my first post and it's a problem related one so I'm really sorry if I've put this in the wrong subforum.
Basically my PSu is making an odd nosie, it's kind of hard to describe what it is, you can hear it when you reach the welcome screen in windows (it's not very loud but you can hear it even when not near the computer), you can't hear it during POST and where it tells you what hard drives and stuff you have connected (rubbish terminology I know). After you pass the login screen in windows it quietens down but it's still there. I originally thought it was a faulty PSu as I had a fairly cheap one (OCZ Stealth Stream 500W) so I bought a better PSU (Corsair TX650) however the noise is still there and on both PSUs and it sounds like it's coming out of the rear of it.
I've heard that other faulty components can throw up feedback back into the PSU, is this true? Or have I just had real bad luck and got two bad PSUs in a row? The computer seems fine, all the components are working well and nothing seems amiss apart from that noise (it sounds like a kind of crackling/buzzing).
The 1st PSU I never noticed this noise until about 2 months into the PC first being built (I always have my headphones on so I never noticed it) and it's been running solid on the second for maybe another 2 months. A few people have said it could be a faulty capacitor on the MoBo or GPU causing interference (due to both PSU emitting this noise) however they all seem to look fine, no leaking or anything.
Case: Coolermaster Storm Scout
CPU: i5 750
Mobo: Gigabyte P55M UD2 MicroATX
GPU: HIS HD 5770
RAM: 4GB CL7 G.Skill Ripjaw
O/D: Sony Optairc 22x
HDD: Western Digital 500GB
(current) PSU: Corsair TX650
Hope its not some ghost, which does not likes the login screen design, making the noise.. Jokes apart, are you sure its coming from the PSU.? It could be the GPU fan also.. Check out all the nuts and bolts to ensure there is no loose joint which might be making some noise due to vibration.. Sometimes even optical drive bays (especially when on a screwless mechanism) make such noise..
The cause is most likely coils on the board. Despite being on the board, they noise can often be heard in the power supply.
I have had video cards(X1900XT 8800GTX 4870) and even a board(X58A UD5 and K8V SE, but only overclocked for this board) All do this. It is not a defect as such, but is very annoying(much more so with video cards).
You will most likely hear the sound from around the cpu socket as well. For my board, i turned off one of the power savings features in the bios (I forget if it was C1E or Speedstep, will check and report back). Either way, my temps did not climb and the cpu still clocks down at idle so i was happy to find that.
If you are asking how this may happen, Coils like those found in the psu and in the power system of boards and video cards vibrate at different loads. Some people can not hear them. Some are quieter then others.
EDIT, What i disabled was C1E under MIT-> cpu features
Also, I never head this noise much when I had my hardware in a Sonata case. So open cases(Antec 900) will allow this noise out to be heard.