HD Tune — Transfer rates
HD Tune lets us present transfer rates in a couple of different ways. Using the benchmark's "full test" setting gives us a good look at performance across the entire drive rather than extrapolating based on a handful of sample points. The data created by the full test also gives us fodder for a line graph.

To make the line graph more readable, we've excluded the SSDs. The solid-state drives have also been greyed out in the bar graphs to focus our attention—and to keep the graphs from looking like a technicolor mess. The rest of the drives have been color-coded by manufacturer, with the Momentus XT 750GB highlighted in a different shade to set it apart from the other Seagate models.

The Scorpio Black has slightly higher sequential read speeds than the Momentus XT 750GB. Still, the new hybrid is a vast improvement over the old XT. Read speeds on the old XT fall off more dramatically than they do on the other mechanical drives.

Of course, neither the mechanical drives nor the hybrids are within striking distance of the SSDs. Even the slowest member of the solid-state pack has double the average read speed of the Caviar Black 1TB. The fastest SSD reads data at a whopping four times the rate of the Caviar.

Switching to HD Tune's write speed test doesn't change the dynamic between our 750GB notebook drives; the Momentus XT can't quite catch the Scorpio Black. The gap between the Momentus hybrids is much narrower here than it was with reads. So is the distance to the closest SSD, which is only barely faster than the best the mechanical field has to offer.

Although SSDs tend to write slower than they read, the best of the current crop is still well ahead of the Momentus XT. The Crucial m4 128GB offers more than double the average write speed of the XT, and the fastest solid-state drives achieve more than triple the write rate.

HD Tune's burst speed tests are meant to isolate a drive's cache memory.

Although the Momentus XT 750GB can't sustain transfer rates that exceed the speed of a first-generation Serial ATA interface, short burst transfers will make use of the drive's 6Gbps SATA link, if only just. The XT's burst speeds are greater than those of its platter-bound compatriots—and even a few SSDs. This performance also represents quite a comeback versus the Scorpio Black, which is much slower with burst reads and writes.