PCI Express 3.0 is a newly enhanced specification that is expected to be released by this year. However, a recent announcement from Al Yanes, PCI SIG President has confirmed that the specifications release date will be pushed out to next year due to additional time and effort needed to testify and ensure its backward compatibility capability with existing PCI-Express based products.
If you recall, PCI Express 2.0 is clocking at 5GHz which is twice as fast as its first generation PCI Express 1.0 stuck at 2.5GHz. However, due to nature of its 8 and 10-bit data encoding scheme, there is overhead that is needed to be compensated and hence the effective bandwidth is only at 4GTps for PCI Express 2.0, which is no longer sufficient for high end graphics card and gaming requirements. Now with the new definition and technology shift, PCI Express has able to achieved 3.0 specification with bus speed scaling up to 8GHz. Besides, the new data encoding schmets at 128-bit and 130-bit has managed to eliminate the overhead required, boosting the effective bandwidth to 7.99GTps suitable for more intensive graphics requirements.
Regardless of its full capability, there is a need to ensure the new specification is fully backward compatible with existing version which is one of the main reasons that contribute to the delay. Nevertheless, we should expect the new specification to be finalized and released by second quarter of 2010, with the new PCI Express 3.0 compliant devices available by 2011.