Will a PCI-E V2.0 Graphics Card work with a PCI-E V1.0 Motherboard?

"Yes. PCIe is backwards-compatible, so you can use 1.0 cards in 2.0 motherboards and 2.0 cards in 1.0 motherboards.

As to reaching the full potential of your graphics card, it's true that PCIe 1.0 is half the speed of PCIe 2.0. (So a PCIe 1.0 x16 interface is comparable to PCIe 2.0 x8.) But single graphics cards really don't saturate the bus anyway: if you dig around through older tech articles, you'll find a number of reviews of video cards in the x8 PCIe slots of early SLI/CrossFire motherboards. Invariably, the conclusion was that the slower bus didn't hurt performance noticeably at all.

You'll be just fine."

"With a AGP 1x & 2x cards are only compatible in 1x & 2x slots. 4x & 8x only work in 4x & 8x slots.

You can not stick a 4x in a 2x slot.

There were AGP pro slots that had a workaround to allow it but it depended on whether the card could even drop down to 2x speed as most cards could not.

AGP is totally different to PCI-E in respects to backwards compatibility. The only time I have seen PCI-E graphics cards not working was because the BIOS of the motherboard did not allow 1x graphics cards."