Not really, short of swapping the the device ports. At bootup, the video card is going to operate in its most basic mode and only output video to whatever is the first device it finds.

There's no way to alter this behavior since it happens before Windows, or any other OS, loads a driver of some sort to allow you to manipulate settings on the card.

Also, you might want to check whether it's a GeForceFX or a GeForce 8500. The FX line was the fifth generation of cards, so all FX cards were numbered 5xxx. Like the FX 5200, 5500, 5700, etc. An 8500 would be 8th generation.