Hi Oppp7,
I don't think any of the Gigabyte Motherboards actually have PCI-E 2.1 but you would have to check with GTTS for a definitive answer on that.
However, a quick through Wikipedia shows that: PCI Express 2.1
PCI Express 2.1 supports a large proportion of the management, support, and troubleshooting systems planned to be fully implemented in PCI Express 3.0. However, the speed is the same as PCI Express 2.0. Most motherboards sold currently come with PCI Express 2.0 connectors.
You can check through the full item here:
http://en.wikipedia.org/wiki/PCI_ExpressIt seems that PCI-E2.1 is a step towards PCI-E3.0