The most predominant feature in PCIe 2.0 is 5GT/s speed, which includes new mechanisms for software control of link speed, reporting of speed and width changes, and control of loopback. Other new features include:

• PCI compatibility using the established PCI software programming models, thus facilitating a smooth transition to new hardware while allowing software to evolve to take advantage of PCI Express features
• Enhanced Completion Timeout Control, which includes required and optional aspects, reduces false timeouts and increases the ability to 'tune' the timeouts
• Function Level Reset and Access Control Services, giving enhanced robustness and support of certain IOV features (optional)
• Slot Power Limit Changes to allow for higher powered slots, which support the newer, high-performance graphics cards; this new feature works in tandem with the 300W Card Electro-mechanical specification
• Speed Signaling Controls to enable software to determine whether a device can operate at a specific signaling rate, which can be used to reduce power consumption, as well as provide gross level I/O to memory