A xHCI or eXtensible Host Controller Interface is a register level interface which allows a host controller for fire ware or USB. These help in the communication with the host controller driver. They come inbuilt with the OS that you have installed.
Windows 8 drivers have provided much needed support by integrating an interface driver called the eXtensible Host Controller Interface. This driver serves as a common driver for regulating the host controllers of USB 3.0. Windows 8 drivers were put to test by Expreview on a Renesas USB controller with 3.0 support. This was compared to the test result with the Renesas own driver. The USB controller is a μD720200F1 similar to that found on ASUS P8P67 Deluxe motherboards. The other components used for testing were the Orico UE3 16GB USB 3.0 flash drive. They use SLC NAND flashmemory.
The flashmemory was subject to a total of four synthetic tests. These tests were all conducted with a constant hardware setup. There were differences in the performance and these were attributed to the different driver profiles involved with it. The four synthetic tests included HDTune, CrystalDiskMark, SSD, AS and ATTO. The test findings showed us that the eXtensible Host Controller Interface drivers from Microsoft were a slight notch behind the Renesas, a third party driver.
In HDTune, it was found that the Microsoft xHCI driver performed better which was indicated by a smoother performance graph. The sequential speed test revealed that the speeds between the two drivers barely went beyond 2%.
The final product that will support the eXtensible Host Controller Interface driver would be Windows 8 drivers. This makes it easier to run USB 3.0 host controllers and its associated compatible devices immediately after the Windows 8 installation. Even though the update cycle of drivers provided from Microsoft is slower, they are at times found to be more stable.
These drivers with its inherent ease and flexibility to use have definitely found its way into the Windows legacy. Though partly down in some areas of the tests it would not affect them much and the stability enhancement that Windows 8 drivers provide definitely makes them a favorite. Now what remains to be seen and experienced is the speed of these USB 3.0 devices.