Hello guys!
 
In november I bought the PSU "Supernova nex750 b1". In the beginning it worked out great (but damn the fan is pretty loud tho) with my graphic card (gigabyte windforce x3) but after around 2 weeks I got some serious coil whine issues. I first sent in my graphic card to the shop (because of all the 970 problems) but I soon got it back with the words that they couldn't simulate any weird noises. Back home I plugged it in, and damn sure my pc still sounded bad. 
 
I contacted the EVGA support and after some weeks I got a new powersupply, I didn't have time with my pc for a month or so but for maybe 2 weeks ago I started to use it again. But even with the new powersupply the sound is still there, almost exactly the same too...
 
The sound is only audible under graphic card load (maybe because that stresses the most?) and if I cap fps so that the card won´t go on max speed the sound disappears. But this is not really a good solution (because it won´t work very well in games <60 fps) and I really wanna get this fixed (my first homebuilt pc). The fps doesn´t matter, as long as the graphic card is uncapped and under load the sound is there, and the sound differs to according to what the monitor is showing (different games, benchmarks, stresstests, looking on different things in the same game etc). 
That´s why I really believed that it must be the graphic card that made the sound, but today I really tried to locate the source, and according to my ears it is the PSU.
 
As I said earlier this is the second supply of the same model I have, and I´m not sure what I should try.
Do I have to buy a totally another PSU model (because this one doesn´t work with my particular graphic card)? Or is it actually the graphic card that is faulty and won´t work with any PSU?
 
I sadly don´t have an extra card or supply so I can´t do much by myself, but the PSU only reacts to graphic card load.
 
Here is two videos from 2 different applications so you can here what it sounds like (in the first video is still thought it was the graphic card):
      youtu be.com/watch?v=gnuAdQUVjI0  This is from Rome Total War 2. And yeah, in the morning I still believed it was the gpu...
      yout ube.com/watch?v=M51hA7pquzw  And this one is occt with powersupply stress test.
 
PS. Sorry for breaking the rules, but it´s kinda hard to explain. And technically it´s not an URL ;)
 
I´m really wondering what I should do...

Vlada011
Ohhh this is nasty. This is bad.
I never heard in life something like that. 
This is very disturbing. 
Wait, you installed 3x GTX970 on 750W Bronze?
That's not good, but again is not reason for coil whine.
If you again have problem with same model of PSU I would go on some stronger and Gold PSU.
I don't see other solution. Simply for 3xGTX970 at least 850W need... PSU need enough Amps and more to hold everything properly.
And with 850W fan should work constantly. 

That´s the name of the gpu! Stands for 3 fans. Got no idea why I have coil whine, can it be the cables? I re-used the ones from the psu I sent in. It´s really annoying as you might guess, earlier I really thought the noise was from the gpu, would have been a lot easier to RMA...

For coil whine no simple and easy explanation. 
It's not danger for components and only chance to get rid of that is to destroy warranty, if some good electrician found exactly source of coil whine to put hot glue or something similar, but sometimes is impossible to find source...
I can bet both of your PSU are good and maybe in other house or other PC, or other components everything could be different.
Best way is I can tell you to try with other PSU platform, that's Super Flower EVGA G2 models. 
My friend call me once to check is that coil whine from his PSU, noise was much higher frequency but not so loud than yours...
He suspect on PSU...
When I go there it was obvious that noise is louder in part around CPU area, I tried with 3 graphic card from his house and noise didn't stop or didn't change tone in full load or idle, always was same, almost like come from USB connectors....One part was interesting too, he explained that he tried more than 3 power supplies and noise was still there with same tone and no sign that noise clearly come from PSU.
But you say you are absolutely sure that's PSU.

I am also having this problem too. Same PSU with gigabyte windforce x3 r9 280X but my computer shutdowns whenever there's games or benchmarks >1000fps. I wondering if it is worth it to RMA or just to buy a new PSU with higher wattage and/or 80 plus certification. 

I still hear coil whine at over 60fps like ProHitZ, it just that i was wondering if the coil whine and shutdown at extreme fps is normal or sign of a bad psu.
The normal resolution i have is @ 1680 x 1050 if it has anything to do with it.
 

I think it was my gpu after all. I tried it on a third psu and still got similar noise (coil whine or something) under the same circumstances. I guess it´s good that I found out the faulty component, but I´m pretty mad at the store that told me nothing was wrong with the card, costed me months of work and annoyance.
 
I hope you solve your problem too jrx755, but it does not sound good with the shutdowns :p

Having Coil whine too EVGA SuperNOVA NEX750B Bronze google search brings many supernova owners reporting same issue. im RMA mine and apparently version b2 they fixed this problem.
 
AMD FX8350
ASUS Sabertooth 990fx r2.0
EVGA GTX 770 2GB
 

google it. newegg and amazon is littered with bad reviews on this psu.im not making it up go google around 
also another complaint is the fan being too loud