I just received parts for a new computer last friday.
Motherboard: ASUS P8Z77-V LX2
PSU: Corsair TX550M
GPU: XFX Radeon HD 7870
RAM: Corsair Vengeance 16GB PC1600
CPU: Intel Core i5-3570K
CPU Cooler: Corsair Hydro Series H100i
Every time I run the system, this annoying high-pitched sound appears from the motherboard (i think).
It is almost constant, sometimes it stops for a minute, but eventually continues. It also doesn't change with my computer's activity level.
The sound is not extremely loud, but loud enough to be annoying.
I tried another PSU in the system, that didn't help. I also tried disabling C1E, C3 and C6 states in the BIOS as suggested by other threads; no luck.
Here's a link to the sound it makes: http://picosong.com/3DNy/ (It is recorded from the back of the motherboard where the CPU is placed). There's some background noise in the recording, but it's the 'eee'-part of it.