Hi, many apologies for adding to this thread so late, but I am having very similar problems and it would be a shame to start all over again!
I was convinced the buzzing was coming from my MSI R6950 graphics card so I replaced it with a similar cheaper one (VisionTek 5450). The buzzing has much improved, i.e. it is quieter and kicks in less frequently. However, under load it is still there. At this level I am wiling to tolerate it if what I'm hearing is true; it's to be expected cap whine.
However, as I'm in the process of RMA'ing my R6950, I'm worried the replacement will just be the same. Is it possible that there is some fault in my motherboard that is causing this noise based on the load it is taking from the graphics slot/processor? Bigger more powerful graphics card = more whine? Should I RMA the motherboard too? (I really don't want to as it took me forever to put it together!). I have Prime95'd my build and of course during the testing the whine/buzz is constant, but the system appears stable as it is passing the tests and not crashing (only did it for 2 hours though). So shall I just accept it?
I have had similar problems in the past and it has been fixed by replacing out the graphics card, however, it has not completely done the job this time. I really think I won't bother in future with doing my own builds... it's too much stress!
Thanks for listening. Any thoughts are much appreciated, I have digested this thread with interest.
Yes, I am a bit OCD
I have: Intel i5-2500k
ASRock P67 Extreme4 Gen3
2x4GB GSkill Memory
Intel 510 series 120 GB SSD
Hyper 212+ heatsink
SeaSonic X750 Gold 750W PSU
MSI R6950 Twin Frozr III but switched out to a VisionTek HD5450 temporarily