Once again, there is no logical leap that goes from for instance "my old 6970 worked without coil whine on this mobo therefore the mobo is fine with 290's or 780's".
They might be they might not. For the cost of a motherboard, in most cases cheaper than psu's and certainly than the graphics cards you're trying, it's mad to not try a different mobo, it's as simple as that.
There is no logical connection between a motherboard working with one card, therefore it WILL work fine with others. Theoretically it should, that doesn't mean it will and considering the effort and expense used, not trying another motherboard as said, is madness. If 1 out of 30 290's is quiet enough for you on the mobo, either you got 29 bad cards, or 1 bad mobo.... want to have a guess at the odds on each scenario?
You constantly have problems, and have two constants.... but are unwilling to change them because of an illogical conclusion you've made.
As said, I'd maybe, maybe RMA the first two cards before trying a different mobo and psu, but in reality, due to the time/cost/effort of RMA's, I'd try them in a different mobo maybe first thing. I'd be very surprised if it was CPU, it's very unlikely, but possible.
It's also by the way, possible that it is software but people don't think about that.
It's been so long as it hasn't happened for me lately I can't even remember precisely what happened. Something along the lines of my headphones would make a weird screech type noise, low and not absolutely annoying, if I closed a certain program.
Motherboards are all different, interference from things like wireless chips, audio, others, are all possible but not a particularly likely cause.
As said, we're not talking about hearing, I've seen and importantly heard videos of coil whine, it's pretty obvious and I've yet to have a card in a decade that has it. I hear and am sensitive to plenty of annoying little noises, fans, other things, coil whine either very quiet or very obvious would absolutely be noticed. Most people on here still don't have coil whine, the ones that do post because they have a problem, the ones that don't have coil whine rarely make posts and start threads to say "I don't have coil whine". Most cards don't have it, trying almost 30 of one type of component while keeping two things constant is barmy.
EDIT:- as with Rofflay, if you're sensitive to noises then you'll just find another one, why have the computer so close. Years and years ago I drilled a few holes in the wall to a spare bedroom next door and stuck computer in there with extension cables. It fast got irritating changing cd's and dvd's... this was back when I used them. Now, small amounts of psu fan noise, graphics card fan, all in the next room. Not only do I not hear the cars when near silent in the same room, when in the next room I can whack the fans up, overclock further, have higher performance and still can't hear it, it's great.
