First of all, PCI-Express 1.0 runs at a maximum of 2.5 GT/s, while PCI-Express 2.0 doubles this rate at a maximum of 5 GT/s (gigatransfers per second).  

• In order to run an EVGA GeForce graphics card in PCI-Express 2.0 compliance, you need both a card and a motherboard that supports this technology.

• If you have a PCI-E 2.0 card, but your motherboard does not support this technology, your card can still run on this motherboard, since it is backwards-compatible.  However, it will not be able to run past the maximum transfer rate of PCI-E 1.0.

While these newer graphics cards are PCI-E 2.0 compliant, it does not mean that they can fully utilize the full bandwidth limit (5 GT/s) of the x16 slots.

If a card is PCI-E 2.0 compliant, that simply means that it can at least reach higher than the maximum transfer rate of PCI-E 1.0 (2.5 GT/s).