How to tell if you have a regular pci-e or a pci-e 2.0?

Im buying a video card that interface type is a pci-express 2.0 and I want to know if my computer has a pci-e 2.0 16x slot. What i do know is it has 2 regular pci slots and one pci-e but how can i tell if that pci-e is 2.0 or not