The software we use for measuring hard disk drive performance, DiskSpeed32, performs really long tests, since it reads all sectors on the hard disk measuring the achieved transfer rate and plotting a graph.

Normally the hard disk transfer rate varies accordingly to the part of the disk that is being read. The disk transfer rate is higher at the disk's edge, lowering as it approaches its center. This occurs because of the zone bit recording (ZBR): in longer tracks (the ones away from the disk center) there are more sectors and more data is read at each disk spin. Because of that, the software used shows three results: maximum transfer rate (obtained on the first disk cylinders, i.e., on the tracks located near the disk edge), minimum transfer rate (obtained on the last disk cylinders, i.e. on the most inner tracks), and average transfer rate, which is the result that we are usually interested in knowing.

Because of this effect we can also explain the need of hard disk defragging and why professional disk defrag utilities such as Norton Speed Disk allow you to move the operating system files to the beginning of the hard disk. As we explained, data stored on the beginning of the disk are read at a higher transfer rate than data stored in other sectors.

We used a Seagate Barracuda 7200.10 160 GB (ST3160815AS, SATA-300, 7,200 rpm, 8 MB buffer) hard disk drive to perform our tests. First we installed it directly on an empty SATA-300 port on our motherboard to see what the performance of this drive is while it is installed inside the PC. We also installed our hard drive on another HDD USB 2.0 enclosure (Thermaltake BlacX) to compare the results. With Max 4 Active Cooling you will see three results. First, with the enclosure connected to the USB 2.0 port; then with it connected to the eSATA-300 port provided on the rear panel of our ASUS P5K-E/WiFi-AP motherboard; and finally with it connected to a regular SATA-300 port using the adapter that comes with the product.

Some people are complaining that some eSATA enclosures aren’t compatible with the on-board eSATA ports available on some motherboards, so we wanted to check this out. Max 4 Active Cooling proved to be 100% compatible with them.

As you can clearly see, eSATA is the best option to connect an external hard drive to the computer, as it allows the hard drive to achieve the exact same performance as if it were installed inside the computer. As you can see installing the enclosure on the eSATA connector available on the motherboard or converting one of the motherboards SATA ports into eSATA made no difference in performance. eSATA provided a maximum transfer rate 236% higher than USB 2.0 and an average transfer rate 145% higher.