Created own thread as instructed by RAM GUY.
I have had following coil whining Corsair PSUs in last few years:
AX750 -- Currently in use
Lets start debugging the problem:
I have tried using the PSU in different house. In fact total 4 of them, 2 of them 400km apart. I live in Finland and currently live in quite new apartment so quality of electricity should not be a problem everywhere in Finland.
I have tried changing ALL hardware components and even PCs and software. Multiple times actually.
For example for the first AX750 I tried:
Core i7 920 C0 / Core i7 920 D0 -- with and without power saving features
EVGA Classified X58 / Asus P6T Deluxe
3x2GB Corsair Dominator GT 1866MHz / Adata 3x2GB G series 1600MHz
HD 5870 / 2x HD 5870 / GTX 460 / GTX 580 / 8800GTS 512MB
Creative Sound Blaster Audigy / Asus Xonar DX
Intel X-25M G2 80GB / Samsung F1 1TB / Samsung F3 1TB/ WD 500GB
XP / VISTA 64bit / W7 64bit -- of course drivers changed too
2x different houses
Changed ALL cables, monitor etc.
Chieftec 550W PSU -> everything worked. No coil whine.
Enermax Revolution 85+ 850W -> everything worked. No coil whine.
Antec 500W PSU -> everything worked. No coil whine.
For the second AX750 I have tried:
i5 2500K / i7 3930K -- with and without power saving features
Asus Maximus IV Gene-Z Z68 / Asus Rampage IV Formula X79
2x4GB Corsair Vengeance LP Low Voltage 1600MHz (3 different kits)
X800XT PE, GTX 460, GTX 480
Asus Xonar DX
Intel X-25M G2 80GB / Samsung 840 PRO 256GB
W7 64bit / W8 64bit
2x different houses
Changed all cables, monitors...
Chieftec 500W PSU -> everything worked. No coil whine.
Going to buy a Super Flower Golden King Platinum 1000W today to replace this coil whining AX750. Will update the situation although I already know the result based on my previous experience...
So I have changed ALL hardware, ALL drivers/software and even physical location multiple times. And only PSUs coil whining are Corsairs.
Because of this I really have to start avoiding your PSU products until this gets fixed. Ask anything and I will gladly help you because I really want to get this stupid problem fixed from your PSUs (which are otherwise excellent btw) they just are far from the advertised quiet.
I will start RMA for the current AX750 I have shortly. Take this PSU in a very detailed test and see what happens.
The first AX750 had very loud buzz like whine but this current AX750 sounds like a bird singing.
I hope you understand my frustration. I think I have tried far more than a consumer should have to trying to fix the problem and now I have to accept the reality that I have to play safe with my next PSU purchase jsut to be sure. That is why I took the coil whine/buzz problems people have with the AX1200i very seriously. I was thinking about buying it but now I simply don't want to try my luck.