I WANT TO PURCHASE ATI RADEON HD 7750 BUT ITS PCI EXPRESS x16 3.0 AND MY MOTHER BOARD INTEL DG31PR IS PCI EXPRESS x16 1.0 DOES HD 7750 IS COMPATIBLE WITH PCE EXPRESS x16 1.0 AND IF ITS COMPATIBLE WILL I NEED TO UPDATE MY BIOS
The Intel G31 Express Chipset is PCIe v 1.1 period, so there's no BIOS to make it anything more. The HD 7750 is going to be bottlenecked by your LGA 775 CPU to some degree, and the only question is by 'how much.' PCIe 3.0 is backwards compatible, at least on paper, but I haven't seen anyone on a PCIe 1.X MOBO's running PCIe 3.0 GPUs.
Therefore, you're a Guinea Pig. My best guess is the HD 7750 should work but don't expect that 'advertised' or 'reviewed' frame rates.