Since Seagate released the Momentus XT series, it has become a popular choice with notebook users who are usually limited to a single storage drive. It aims to bridge the performance gap between mechanical hard drives and solid state drives without resulting in a massive price premium. Today we are going to look at the second-generation solid state hybrid hard drive from Seagate, the Momentus XT 750 GB.

The concept of a solid state hybrid hard drive is very similar to that of Intel’s Smart Response Technology, which we examined in detail here. Instead of having a separate mechanical hard drive and solid state drive, Seagate has integrated the SSD portion into the 2.5” hard drive enclosure. Despite this, the drive itself looks almost identical to a regular mechanical hard drive.

Seagate Momentus XT 750 GB Hybrid HDD ReviewFigure 1: Seagate Momentus XT 750 GB (top)

Like Intel’s Smart Response Technology, the Momentus XT uses algorithms to identify the data on the hard drive that is used most frequently and caches it to the SSD portion of the drive. The SSD portion of the drive enjoys much faster read and write speeds and shorter response times, so the data you use the most can be accessed more readily. Therefore, installing a Momentus XT into your system should help improve real-world performance such as boot times and loading times in Windows.

Seagate Momentus XT 750 GB Hybrid HDD ReviewFigure 2: Seagate Momentus XT 750 GB (bottom)

The Seagate Momentus XT 750 GB has a formatted capacity of 698.63 GB which means there will be ample space for the media files of most users. It is also much more capacious than any SSD currently on the market at this price point. Seagate has used single layer cell (SLC) memory for the integrated SSD, as it is able to endure more read and write cycles than the cheaper multi-layer cell (MLC) memory before failing. Even if the SSD cache does fail after a few years, though, the Momentus XT will still function as a pure mechanical hard drive with no data loss.

In our tests, we will be using the Seagate Momentus XT 750 GB (which uses Seagate’s second-generation hybrid technology), Seagate Momentus XT 500 GB (which is a first-generation hybrid drive), Seagate Momentus 750 GB (which is also a 2.5” unit), and Western Digital Scorpio Black 750 GB (another 2.5” unit) hard drives for comparison. We will also include results from a solid state drive, the OCZ Agility 3 240 GB, to show how the performance compares. In the table below we compare the basic specifications of these products.

Manufacturer Model Model # Rotational Speed Interface Buffer Capacity
Seagate Momentus XT (2nd generation) ST750LX003 7200 rpm SATA-600 32 MB 750 GB
Seagate Momentus XT (1st generation) ST95005620AS 7200 rpm SATA-300 32 MB 500 GB
Seagate Momentus ST9750420AS 7200 rpm SATA-300 16 MB 750 GB
Western Digital Scorpio Black WD7500BPKT 7200 rpm SATA-300 16 MB 750 GB
 OCZ Agility 3     AGT3-25SAT3-240G NA SATA-600 NA 240 GB
Henry has been taking apart computers since the age of 10, which eventually lead to a career in technology journalism. He's written for numerous leading UK technology websites as well as writing advisory articles for Best Buy.