HD Tach
We tested HD Tach with the benchmark's full variable zone size setting.

These tests should give us a good sense of each drive's maximum achievable sustained transfer rates. The X25-M proves the fastest in the read speed test, followed closely by the Vertex, as the Summit trails more than 20MB/s off the pace.

The X25-M falls to last place in the sustained write speed test, which shouldn't come as a surprise given the drive's relatively sluggish 70MB/s write speed rating. The Summit is nearly 100MB/s faster here, and the Vertex is a further 25MB/s quicker.

It's interesting to see how much these transfer rates conflict with the results of our real-world file creation, read, and copy tests. The Vertex looks like the bee's knees in HD Tach, but it doesn't fare nearly as well when creating, reading, or copying actual files. This is why we don't rely solely on synthetic benchmarks to evaluate drive performance.

The X25-M has a slight edge over the Summit in HD Tach's burst speed test. There's no difference in performance between Summit firmware revisions here, and there wasn't with the sustained read and write speed tests, either.

Curiously, the Vertex only manages 186MB/s in this test. The drive's 64MB cache should be able to keep up with a 300MB/s Serial ATA interface, suggesting that the Indilinx controller is slower than the others when handling burst transfers.

As far as HD Tach is concerned, all these drives deliver instantaneous seek times.

HD Tach's CPU utilization scores are nearly within the app's +/- 2% margin of error for this test. I'm going to call it a wash.