I'm looking to add a third display to my Windows 7 machine. The main GPU is a Radeon HD3600 PCIe board, and it does fine for the two displays available. I only have one PCIe slot, so I'm trying to make an old PCI Radeon board work in parallel. It's an R92P 128MB. Windows simply recognizes it as a "Standard VGA Graphics Adapter", however I'm getting the absolute most helpful error, Code 10 ("Device failed to start").
First question: is there any hope?
Second question: most topics on the "Device failed to start" issue basically tell you to make sure your motherboard is set to "Assign IRQ to VGA". There is no such option in my BIOS (Gigabyte EP35-DS3l rev F4), however I found that I can seat the board in a PCI slot that didn't share its interrupt with any system devices, and assign it any IRQ I want. However, no matter what I assign it, it always gets IRQ 5 which is shared with half a dozen devices. My guess is that the device absolutely must have its own IRQ, but I can't get the BIOS to assign one that isn't shared.
Third question: What else could I be missing here?