The Bottom Line
Unless you need SATA 6Gbps support, choose a USB 3.0 card that plugs into a PCIe x1 slot, and for best performance, make sure the slot and the card both support PCI Express 2.0.
Add-on Cards for Laptop Computers
Most of the vendors that make USB 3.0 cards in the PCIe x1 form factor also produce cards for the ExpressCard slot common on most recent notebook computers.
As with the PCIe cards discussed earlier, all of these products currently use NEC silicon. However, there are differences in accessories that might make the difference in what you buy:
- ExpressCard/34 to ExpressCard/54 converterMost ExpressCards use the narrow 34mm (ExpressCard/34) form factor. To help these cards fit more tightly into the ExpressCard/54 slot, some vendors include a converter.
- AC connector and adapterExpressCard USB 3.0 cards provide only 100mA of current per port, compared to the 900mA of current produced by PCIe cards. If you plan to use devices that use more than 100mA of power, you will need to connect a 5V AC adapter to the card to provide 900mA per port. Some vendors don’t include the adapter, so check with the vendor for availability and specifications.
Motherboard Replacement and New Systems
Virtually all major motherboard vendors now offer USB 3.0 ports in their latest product lines as well as SATA 6Gbps ports. These motherboards are primarily designed for the latest Intel Socket B and AMD Socket AM3 processors (all of which use DDR3 memory), so if you are planning to update a computer that’s more than two years old, you will probably wind up replacing your processor and memory as well as your motherboard.
Although current motherboards with USB 3.0 rely on the same NEC controller chip used in add-on cards, other motherboard features have important roles to play in how well USB 3.0 will work on a particular motherboard:
- Chipsets and PCIe versionCurrent AMD chipsets provide more PCI Express 2.0 lanes than most current Intel chipsets. Intel chipsets provide a mix of PCI Express 2.0 lanes and slower v1 lanes, while AMD’s 700 and 800 chipsets use only PCI Express 2.0 lanes.
- How PCIe lanes are allocated to onboard devicesAccording to Tom’s Hardware, three common methods on Intel motherboards include using only PCIe v1 lanes for USB 3.0 (and SATA 6Gbps), routing USB 3.0 and SATA 6Gbps to PCI Express 2.0 lanes normally used for graphics, and using bridge and switch chips such as the PLX8608 chip to dynamically allocate PCI Express 2.0 lanes between devices as needed.
- PCIe lane assignment Some motherboards’ BIOS setup programs permit you to determine which PCIe resources have priority in terms of numbers and types of lanes.
For a detailed discussion of the impact of chipset selection and BIOS configuration settings on USB 3.0 performance, see this Tom’s Hardware article: USB 3.0, SATA 6Gb/s, Motherboards, And Overcoming Bottlenecks: Why PCI Express 2.0 Matters.
When USB 3.0-equipped computers hit the market, these same considerations will exist, especially for users who want to get the most out of their systems’ newest technologies.