It will support that card. PCI-e 2.0 and 3.0 are interchangeable. You can use that graphics card in your motherboard if your power supply will allow it <- important.
To support PCI Express 3.0, you must install an FM2+ APU, otherwise it will run at PCI Express 2.
For a 750Ti, PCIe 2.0 slot should suffice in terms of performance if thats what you are running. Heck even PCIe 2.0 x8 might even be enough; its plenty for my 6970.