By now, most enthusiasts are aware of the bold claims concerning the performance potential of USB 3.0 peripherals, but supporting controllers have only recently started dribbling onto the scene. However, fully testing the capabilities of this technology would require some kind of data device that is at least as fast as the fastest controller and such a device does not yet exist (we'd need something capable of pushing more than 500 MB/s).
We probably shouldn’t expect to tickle the upper reaches of what USB 3.0 can do any time soon. After all, it was more than a year after the introduction of “hi-speed” USB 2.0 before devices were able to offer 35 MB/s speeds, which still fell far short of the interface’s rated 480 Mb/s (60 MB/s) specification.
Due to a similar lack of adequately-speedy devices and an even more fantastic-sounding data rate limit, it could be years before we have a chance to push USB 3.0 as far as the interface will go. Yet, the relative scarcity of USB 3.0-enabled peripherals at this point in time doesn’t prevent us from taking a closer look at the way USB 3.0 is being implemented on the latest motherboards. If the results are good, you can be sure we'll see more and more hardware hitting the scene with support for the interface.
Before we examined the “how” of USB 3.0 implementation, we asked ourselves “why?” Wasn’t eSATA good enough? Casual observers could cite the fact that its 5.0 Gb/s interface is potentially faster than the 3.0 Gb/s supported by eSATA, but insightful readers know that eSATA already outpaces consumer-level storage solutions and is due for an update to 6.0 Gb/s soon. Thus, while USB 3.0 is generally promoted as a performance enhancement, its primary raison d’être might be as a solution to eSATA’s problems.
The first problem USB 3.0 solves is that, unlike SATA, it’s not limited to ATA and ATAPI devices. Designed to function like a PCI Express (PCIe) 2.0 external link, combining it with USB 2.0 on a single jack provides connectivity similar to what ExpressCard slots offer with which so many notebook users are familiar. We look forward to seeing it adapted to a similar variety of devices, such as video capture and graphics cards. Borrowing power from the USB 2.0 interface with which it co-exists, USB 3.0 becomes a more convenient solution for portable drives compared to non-powered eSATA. USB 3.0 also specifies higher amperage capacity for the USB 2.0 power pins it shares, making it a better solution for portable storage than even the combination USB 2.0/eSATA connections present on some motherboards and thumb drives.
But perhaps the most important of USB 3.0’s advantages is that, by being designed for removable devices from the beginning, the standard isn’t likely to meet the engineering abuses that have prevented onboard SATA/eSATA controllers on many motherboards from supporting the “Safely Remove Hardware” function of Windows. Thus, while USB 3.0 might be “just another interface” from the storage perspective, improved flexibility makes it an important step away from the eSATA interface against which it competes.
With the question of USB 3.0’s relevance settled, let’s take a closer look at how manufacturers are implementing it.