Hi,
I am getting a Gigabyte Radeon HD7870 2GB Overclocked GPU, and in the Card Bus section of the description, it says: PCI-E 3.0
My current Motherboard is an ASUS F1A75-M-PRO Motherboard and for it's Expansion Slots section of the description, it says:
1 x PCIe 2.0 x16 (blue)
1 x PCIe 2.0 x16 (x4 mode, black)
1 x PCIe 2.0 x1
1 x PCI

My question is will I be able to use the GPU I'm (hopefully) getting with my current Motherboard. And if so, at what cost - meaning will I lose any features or functionally by using a 3.0 GPU with a 2.0 PCI-E Slot?

Thanks for any advice:)

U will loose the dif in bus speed other words your card will operate slower.

Look here:
Using a PCI-E 3.0 in a 2.0 slot

Some day you'll have a 3.0 slot, right?