To illustrate this discussion I tested one of the first Serial ATA hard drives supporting NCQ. This was Maxtor MaXline III. We measured the HDD performance in “real applications” with the help of PCMark04 test package. The tests were run with the old Serial ATA controller implemented in the ICH5R South Bridge, and with a new controller of the ICH6R South Bridge. All tests were performed in two modes: with a standard driver without NCQ support and with Intel Application Accelerator 4.0 driver with NCQ support.
According to the benchmark results, the Serial ATA controller integrated into the ICH6R South Bridge is faster than the controller of the previous South Bridge version from the very beginning. When we enable NCQ, ICH6 gets even better results, and the boost is quite significant I should say. The disk subsystem got about 7-10% faster in real applications once we enabled NCQ. This way, the use of this technology does really optimize the performance of Serial ATA data storage devices.
In conclusion I would like to mention one more important improvement, which appeared in the new controller of the ICH6 Bridge. Now this controller also supports ATAPI protocol, which allows using Serial ATA optical drives, for instance, with the i925/i915 based mainboards. Since ICH6 has only one Parallel ATA channel now, this innovation is of very big importance.