Windows 7 - USB 3.0 transfer speed...

Shouldn't we have a "Show us your USB 3.0 performance..." sticky?

There are few 2.5" external hard drive enclosures with USB 3.0 external interface with SATA III internal interface; the majority of them have SATA I/II internal interface. Either one of them will max out the HDD performance, but the the SSD can easily max out the SATA I/II throughput.

Test setup:

1. Enclosure: COOLMAX HD-250TN-U3
2. SSD: OCZ Vertex3 60 GBs

Interfaces nominal transfer speed:

• USB 2.0: 480 Mb/s, or 60 MB/s
• USB 3.0: 5 Gb/s, or 625 MB/s
• SATA II: 3 Gb/s, or 375 MB/s
• SATA III: 6 Gb/s, or 750 MB/s

The nominal transfer rates are lowered by 8b/10b encoding used for data transfer control by about 20%. The actual maximum for the interfaces are:

• USB 2.0: 40 MB/s
• USB 3.0: 475 MB/s
• SATA II: 300 MB/s
• SATA III: 600 MB/s

Based on these numbers and the setup at hand, the read speed of the external USB 3.0 enclosure with the OCZ Vertex3 SSD should be close to 300 MB/s.

Well, that's not the case as shown in the AS SSD benchmark:



The CrystalDisk Mark score is pretty much the same:



Just for comparison; here's the Seagate 1TBs eSATA III HDD CrystalDisk Mark score:



It is conceivable that the OCZ Vertex3 in a eSATA II or III would run circles around the same drive in USB 3.0 external enclosure...

Somewhat disappointing that the setup does not even max out the USB 2.0 interface as shown in the AS SSD benchmark below, when the enclosure is connected to USB 2.0 port:



Certainly the quality of the external enclosure has a lot to do with these numbers and so do the drivers on the system.

The test had been somewhat disappointing that the performance results had been a third of what they should have been. An HDD write speed outperforming the write speed of the USB 3.0 with and SSD, that's a pretty good turn off.

While some time had passed since the lest time I've looked at the performance of the different interfaces, there isn't much that has changed. Other than the devices are more "affordable" nowadays, it's pretty much the same. SATA and/or eSATA still run circles around the USB interface.

Maybe there's a reason why we don't have "Show us your USB 3.0 performance..." sticky...