Manufacturers are beginning to release details of the first external hard disks based on USB 3 technology - but they are falling well short of the technology's stated maximum speed. USB 3, which was showcased at last week's Intel Developer Forum, is technically capable of hitting data transfer speeds in excess of 600MB/sec. However, the external hard disks announced by companies such as Buffalo and Freecom are only hitting a fraction of that throughput. Buffalo's HD-HXU3 comes in capacities ranging from 1 to 2TB, with claimed "SuperSpeed" transfer rates of up to 125MB/sec. Freecom's Hard Drive XS 3.0 also tops out at 2TB, with a stated maximum transfer speed of 130MB/sec. So why the shortfall? "The interface will hit speeds of 600MB/sec or more, but the hard drive itself will only achieve 125MB/sec," a Buffalo spokesman told PC Pro. "The hard drive is the bottleneck."
Nevertheless, the USB 3 drives are a sea change from today's USB 2 models, which typically top out with read speeds of around 50MB/sec due to the constraints of the interface.
Buffalo's drives are expected to arrive by the end of the year, while Freecom's model will be available from November, with prices starting from 119 Euros (£109) for the 1TB model. Both will also offer controller cards with their hard disks so that desktop owners can take advantage of the USB 3 speeds before the USB 3 ports start arriving in new PCs.
Microsoft is expected to announce USB 3 support for Windows 7 shortly after its 22 October launch
