The four HD Tach metrics that we sampled for each drive are Random Access, which is largely dependent on spindle speed of the drive, Read Average, Write Average and Burst Read throughput. Again, Read and Write Average scores are what we would consider the most meaningful to the end user. On the other hand, Burst Read is typically tied to a drive's on-board caching and SATA interface speed.
After the WD7500AAKS's apparent dominance in the eariler tests, we finally find a kink in its armor -- the HD Tach Burst Read test. While it does outperform the other Western Digital drive and the Hitach drive in Burst Read, it can't quite touch the scores put up by the two Seagate drives. Once again, we have to stress that we put more weight in the Average Read and Average Write speeds, and these are two areas where the WD7500AAKS dominates again.