Recently I started to notice annoying unstoppable buzzing/rattling sound coming from my pc. its almost a continuous sound, but it gets noticeably louder and faster when I scroll my mouse up/down, watch a video online or open vlc player, etc.. even if CPU,GPU and memory usages are low the noise is still there. I think this sound is located near the PSU, so most likely its coming from the PSU (I'm not 100% certain though). the weird thing that this sound gets noticeably quieter only when I enter the bios. any explanation to that?. there is also another weird thing.. I guess that noise is gone when I play a high demanding game, I'm not sure though, maybe the fans spinning cover over this sound. I recently cleaned my computer case with blower, cleaned most of the components except the PSU fan. my pc Temps are normal on idle and under load, I never had problems through the 4 years when my pc is under load. I tried disabling C1E, EPR, C6/C3 from the bios.. but problem still there. Motherboard: Gigabyte H61M-S2p Ram: 8GB GPU: Sapphire HD 7870 XT 2GB CPU: Intel i5-3470 HD: WD Blue 1TB PSU: Thermaltake 500W model TT- 500 NL2NL Case: Thermaltake commander MS-III Windows 7 64 bit. any Help would be appreciated.