GTX 570 incompatible with 790i ?

I have an EVGA 790i Ultra SLi and I don't understand why it wouldn't be compatible.

Have you tried installing it in a different slot? Or better yet, have you used Driversweeper to remove ALL of the old drivers before installing the new ones? I would take a gander that it's a driver issue and not a hardware problem.

There's a few things to try, but first get MSI afterburner and tell us what your clocks and voltages are.

...and in bios make sure your pci-e to nbridge is set to 100mhz and not auto.

If I install it in a different slot (with the GTS 250 removed as well) I wouldn't get any display.

I have tried to get the above config to work by installing each new combination of drivers on a vanilla install , that too both on Win 7 and Win 7 sp1.

Clocks and voltages as per MSI Afterburner :
Core voltage : 962 mV
Core Clock : 732
Shader Clock : 1464
Memory Clock : 1900

In BIOS
pci-e to nbridge/ MCP PCI Express Frequency : is indeed 100mhz
Adjust PCI Express Frequency : 100 Mhz

Ok shouldn't be any problem there unless the voltage is a tad low. I'm running my gtx570 at 900/1800/2000 at 1.1 volts solid, but I had the same problem you did back when I was experimenting with clocks and bumping up voltages. But for your clocks, 1.0v should be fine.

What version is your bios? Maybe it needs an update.

I'll try increasing the voltage and post the results. My GPU's BIOS version is 70.10.17.00.03

Ok, I increased the voltages to 1.0V but it didn't work. I even tried .913 .925 .938 .950 .963 .975 .988 1.1V as well but nothing seems to work. I'm thinking of reconsidering my GPU stability (problem with the GPU itself) as only upon adding and using the GTX 570 does my system lose its stability. is there any program like memtest to check my GPU ?

Just FYI, I have already used MSI Kombustor and my card was able to deliver about 3,00,000 frames in a matter of 48 min at x16 AF.

Shouldn't be any compatabilies; 790i even supports PCI 2.0, so that can't be the issue...

On the 790i series of motherboards, you HAVE to have the GPU installed in the primary GPU slot, or you won't be able to POST [Tried that once on my XFX 790i Ultra...].

I wonder if its more a game problem as opposed to the GPU? I mean, you ARE getting to windows, so that means the card is working to that point..

ok I think I have figured it out. I rechecked my graphics card on my friends PC and there weren't any problems, I played Crysis 2 for straight 1.5 hours. Then I thought when I first bought the 790i none of the nforce drivers except the 9.64 worked perfectly. So I installed Win XP 32 bit, installed just the 266.85 drivers and voila my games are't crashing anymore. Apparently the chipset drivers that Windows 7 x64 deploys were somehow conflicting with the GTX 570 and not the GTS 250 (as the main card) and was hence showing dual behavior. I am slowing installing other drivers on Windows Xp while creating retore points and post results after playing the above games for an extended period of time.