Please advise and recommend.

Hello, I want to replace my power supply, it's fan is making an annoying sound which really is stupid, when its on low load the sound increase but while on full load I don't here it much specially if I am gaming it just fades. While watching something or hearing music I hear nothing unless I mute the sound. It's a low krrrrkrrr krrr sound which is so strange like the fan is not spinning fast enough or something, when I put my case on its side or upside down the sound disappears and I don't want to fully disassemble the PSU there is no sense in doing that unless if I am going to change the fan which is still not an option because I am not sure if I will find the same spare part, I clean my gear every 6 or 8 weeks which rule out dust problems so what should I do please help, is there something wrong with the PSU or is it only the fan and can I just replace it!!? I had that PSU for almost 14 month now, I wanted to change my case I had it since 2008 so I want some look change and its USB 2.0 front panel are not working proper now they sometimes not read well or give the error massage that they are not working fast enough so I may get a new case with a USB 3.0 front panel because the current one doesn't have any. Thank you for your help.


Intel Core i3-3220
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CORSAIR Vengeance 8GB (2 x 4GB) DDR3
NVIDIA GeForce GTS 450 1GB
Western Digital Caviar Blue 1TB SATA 6Gb/s WD10EZEX
HEC Mid Tower with Coolermaster eXtreme Power Plus 600W