Ok... here's my predicament... I just got an ASUS Crosshair II Formula mainboard. I put in my RAM sticks and CPU... runs great. No sweat. I was just doing a quick run, and was using the IGFX for my display. After I cleared all that stuff, I power down, and install both of my GTX 260's... I turn it on... not a damn thing. Everything else was running fine, just no video. It's like the board doesn't recognize the cards are even in the slots. At first, I figured I just bought a bad board. Then, I thought maybe my PSU wasn't pushing enough juice. It's a Thermaltake Black Widow 850W... plenty for this rig. So, I take one card out and run it... still nothing. I flashed to the newest BIOS (ver. 1802), and still no joy. So I get curious... I dig out my old ATI HD 2900XT and this little HD 4670... I plug in the 2900... and it booted right up scribbles and crap on screen, obviously detected... I mean, the card's been fried for months, but I use it for crap like this. it's a 2900XT... this thing was created for the sole purpose of raping your PSU! the 4670 worked fine too... I'm at a total f*cking loss. anyone got an idea?
This has happened to me on an ASUS M3N78-EM and I still don't know what's the cause of this. iGPU works fine and with the bios set to the pcie vga first, it still doesn't work. Bios updates did nothing, and radeon cards work fine (i didn't try with other nvidia cards). I tried my gtx260 in two of my friends' rigs and it works... i REALLY don't know what's up with this... Best option is to RMA the board.
u said that it detects ati cards like ati 2600xt right? then your pcie video card port reads the gtx 260, u said it runs fine but no video, , , i have a question sir? have you disable the IGFX first before installing the nvidia gtx 260 , maybe try to disable that before installing those gtx 260 cards . . .i have this board and a gtx 260 card and it works for me . . . hope that helps sir ... thanks