I think he (The OP) doesn't want his IGP to be on, he only wants to use the PCIe GPU with the multi monitor setup he has going.
Just display the onboard Video thru the BIOS and you'll have the displays working.
Or change the order in the bios if you can't disable it, to
PCIe first then IGP or Onboard....
How is he going to access BIOS if he has no display? Like the OP said, he's done this a hundred times and he's EXPECTING the integrated graphics to work. He never said he didn't want it to. Removing the CMOS will simply reset the BIOS. There's no harm to that. Just simply configure your settings after.
"I've done it a hundred times and everytime it reverts to my motherboards intergrated graphics on reboot."
This is NOT the problem. He's saying that he does driver sweeping a lot and everytime he does it, he is able to get a display on the IGP. But this time around, there is no display AT ALL. You're interpreting it differently, not me.
Removing the CMOS battery is your next option. Like twoboxer said, turn off your PSU, unplug the power cable, and then remove the CMOS battery. Keep it out for at least 2 minutes. This will reset your BIOS settings and hopefully have the computer detect your onboard graphics as the primary graphics so you can use that to get a display.
Ok Ill try that. It's just odd how this is happening. Everytime I did this it's never been a problem. My GPU (xfx 4870) has the ability to switch to the onboard graphics when no drivers are available. So I never even had to plug anything into my motherboard. This is all very strange......
Did you remove the ATI card and then try to boot the computer with the onboard display? Even though you didn't touch them before, try reseating other components of the computer as well, specifically the RAM.
As skolpo said, the next step would be to remove the vid card completely and plug the vid cable from integrated graphics adapter port to monitor.
Also, leave the case open and tell us what you see when you attempt to power up. May not help, but would like to know if cpu fan comes on and stays on, on and then off, no lights on the mobo or some lights, that kind of thing.