bob16314It's the video card BIOS programming and it's voltage regulation components that dictate how much power the card is allowed to draw from both the PCIe slot and any 6-pin/8-pin supplemental power connectors. Specifically, PCI-SIG (industry standard) specs dictate that up to 75W (6.25A) can be drawn through a PCIe slot, up to 75W (6.25A) can be drawn through a 6-pin supplemental power connector, and up to 150W (12.5A) can be drawn through an 8-pin supplemental power connector, at 12V..Your video card likely failed for some reason and caused that by allowing too much current (Amps) to be drawn through the connectors and the PSU happily obliged, because it could. A single-rail PSU like an 850 GQ has no per-rail Over Current Protection which is great for stability, but it's a double-edged sword..A multi-rail PSU would have probably tripped the Over Current Protection before that damage occurred, that's what OCP is supposed to do..Intel writes PSU rules in their Power Supply Design Guides that should be adhered to and had done away with the multi-rail requirement some years ago due to more modern hardware demanding more power and hardware manufacturer outcry. Long story short = A PSU will supply only what it's asked to supply, up to a point, by the hardware, even faulty hardware..Almost certainly not the fault of the PSU. Power Supply Design Guides (and other stuff, bottom of page)Power Supply 101: A Reference Of Specifications (PCI Express Auxiliary Graphics Power Connectors)Debunking Power Supply Myths (Connectors and the 12V Rail Issue)
enrique145I guess one has to become a computer and electrical engineer to not be afraid to use a GPU and a PSU. I read 750W PSU on the box of the GPU and assumed the 850w PSU would suffice, but wrong I was. The 7990 is out of warranty, so to the garbage/recycling bin it goes. I would post pics, but there was no physical damage to it. I stopped the burning madness on time, before the 8 pin connected to the GPU melted too. All I know is, the GPU does not work anymore since this event. Well, as soon as that replacement arrives, on sale it goes, and so the other parts of the computer. I will buy a prebuilt computer, probably a Mac and forget about building my own computer again. It is definitely not for me. Thanks a lot for your opinions, I really appreciate them. Good Luck!