The GPU/PSU interactions have been going on for quite a while. Many video cards seem to throw a lot of signal garbage back into the PSU (and anything else connected in the system). Due party to poorly engineered VRMs in the video cards. Only option here other than being an electrical engineer and making your own (good)VRM system and interfacing it with the card, is to get a good company to make your card. Like high quality names like Asus as compared to some no name crap card or something. It's not only the PSU that gets affected; I think noise in the audio card line is also caused partly by bad video card circuitry. My guess is that if you powered the video card off a different PSU altogether, the system PSU would not make this squealing sound. Sounds like a decent plan, and you COULD power the card entirely off of another PSU, you would have to do a lot of soldering and trace cutting (cutting the power traces that go from the graphics card to the motherboard and soldering wires there to power those traces from another PSU) but I think just powering the card from another PSU's 6 pin power supply would be worth a try.Of course, this is impossible, as the video card plugs into the motherboard, and that slot is powered by the PSU.
One possible solution, not to be messed with at home, appears to be small caps across the DC output terminals -- just something I heard. Yes, sounds logical, but I would be willing to bet that PSUs already have some filter or decoupling capacitors across the DC output. Now the capacity/quality of these caps maybe could be modified, I doubt that would succeed in anything though.
One thing that I would think of would be to connect the ground pin on your wall outlet to the ground on the PSU's DC rails. Let me explain. AC is basically DC, but the + and - switch 60 times a second. So one wire will be + and the other be -, and then will flip, so the first is - and the second is +. Typical household AC does this 60 times a second. (60hz ever heard of it?) (AC is used because it is easier to transport over distances and in great quantities, if DC was used in house wiring the + wire would have to be really thick because of the current going across it and the heat generated, AC splits the heat and current going across into 2 lines) so your power supply (using a bridge rectifier, 4 diodes in it's simpilest form) converts the AC to DC (it doesn't really convert so to say, it more or less splits up the + and - into 2 constant streams instead of them switching back and forth)
But on most power outlets you have the little hole under the 2 prong slots, this is (I think) true earth ground. What someone could try would be running a wire from that earth ground hole, and connecting it to the GND on all of the DC rails for the PC. This would effectively provide a "true" ground to the system instead of the "artificial" ground generated by the bridge rectifier.
Here's the 1 issue with my theory. I wouldn't be surprised if the PSUs already connect the true earth ground to the DC output's ground...if they do my theory is pointless because it's already being accomplished.
MikeC, where does the graphics card throw out signal garbage? It would have to throw it out to the GND line right? It can't throw out signal garbage on the + power lines can it? Or does it throw the signal trash out over the PCI bus? I heard that PCI Express is electrically isolated so that (I assume) if a video card put out signal garbage it would be isolated from the rest of the system...right?
I don't know, I'm not an electrical engineer...[/b]