Portable Performance: Four USB 3.0 Enclosures For Your 2.5” Drive

Never The Twain Shall Meet

The remarkable words of Rudyard Kipling that describe the gulf between eastern and western philosophies might just as easily be used to describe USB 2.0 and USB 3.0 signaling. We hear a lot of references to “backwards compatibility” bandied about in the discussion of USB connectors, but unlike USB 1.1 and 2.0, there’s a lot more behind the change to USB 3.0 than a simple signaling rate. Indeed, the term “backwards compatibility” doesn’t really describe how these interfaces coexist as separate technologies.

Type B cable ends, including Micro USB, USB, and their USB 3.0 derivatives

The easiest-to-describe difference is SuperSpeed USB’s use of 8b/10b encoding, which is only part of what makes the signals incompatible. It’s because of this signal incompatibility that USB 3.0 connectors have an extra five signal pins, which allow USB 3.0 and USB 2.0 to coexist. Coexistence also allows bus-powered USB 3.0 devices to take their power from the previous version’s power pins and the USB 3.0 specification even increases the current limit of the previous-generation connector from 500mA to 900mA.

Differences don’t end at the connector, as SuperSpeed USB also requires its own controller interface. Companies have fortunately figured out how to put multiple interfaces on a single device, such as the ASMedia bridge above. Used in all four of today’s comparison enclosures, the ASM1051 hosts SATA over USB 3.0 and USB 2.0.

The presence of a USB 2.0 controller on USB 3.0 devices means that devices can be used with the smaller USB 2.0 cable, while reverting to USB 2.0 speeds. This could come in handy during an emergency, since replacement USB 2.0 cables are far easier to find.

Thomas Soderstrom
Thomas Soderstrom is a Senior Staff Editor at Tom's Hardware US. He tests and reviews cases, cooling, memory and motherboards.
  • I know this isn't relevant, but what is in the pcie1 slot?
  • Gin Fushicho
    You guys are really benching cases? I figured they'd all be close to the same anyway.
  • Crashman
    SubSonix1I know this isn't relevant, but what is in the pcie1 slot?
    Nothing, the slot is covered by an extended chipset heat sink.
  • TomD_1
    So basically, they all have identical hardware, and IMO all look ugly
  • Crashman
    TomD_1So basically, they all have identical hardware, and IMO all look ugly
    You forgot to mention they all fit in a shirt pocket. That is the most important part.
  • thejerk
    Scraping the bottom of the barrel for non-iPad news?
  • warmon6
    thejerkScraping the bottom of the barrel for non-iPad news?
    Um.... few things,

    1. They haven't been just covering the ipad. They been covering alot of other things.

    2. This isn't news. This is a review. Learn the difference.
  • kelfen
    if ya think about it this is more cost effective per GB to buy one of these and a hard drive then buying a usb drive
  • Good... so I can share my pirated movies more faster?( sarcasm )
  • rooket
    What's the performance like if you use it with a hard drive? Just same as usb 2.0 I'd imagine? Odd that they're only hitting 35MB/sec with USB 2.0. It should go 60MB/sec. Why is this only half the speed?