USB 3.0 Performance: Two Solutions From Asus And Gigabyte

New Motherboards From Asus And Gigabyte

Always trying to stay on the leading edge of hardware development, the first challenge motherboard manufacturers faced in adopting any high-bandwidth controller for Intel’s latest platform is that the chipset doesn’t have a suitable high-bandwidth interface. The 16 lanes of PCIe 2.0 provided by LGA 1156 processors are normally tied to graphics card slots, and any additional PCIe connections must be made through the P55 PCH at a half-rate 2.5 GT/s. A single 5.0 Gb/s PCIe 2.0 lane would have been adequate for USB 3.0, but P55 has none.

Asus’ solution is to add a PLX PCIe bridge, which can be seen in the photo above as the large IC with a silver logo to the left of the power and reset buttons. The PLX bridge converts the P55 Express chipset’s four 2.5 GT/s lanes into two 5.0 GT/s lanes, making it possible for Asus to host its USB 3.0 and SATA 6.0 GT/s controllers at full PCIe 2.0 bandwidth. While today’s article is limited to USB 3.0 implementation, we’ll communicate more details about this P7P55D-E Premium motherboard in a future roundup.

At two-thirds of the price of its Asus rival, Gigabyte’s P55A-UD4P cuts costs by using the processor’s PCIe 2.0 connections to host its high-bandwidth controllers. Two of the primary graphics card’s 16 PCIe lanes supply its USB 3.0 and SATA 6.0 Gb/s controllers, and Gigabyte disables six more lanes to make the upper slot an effective x8 interface. The USB 3.0 and SATA 6.0 Gb/s controllers revert to the chipset’s 2.5 GT/s lanes whenever two graphics cards are installed, to preserve the x8 transfers each graphics card needs for optimal CrossFire or SLI performance.

Thus, users with a single graphics card must sacrifice half of its peak bandwidth to enable 5.0 Gb transfers to the USB 3.0 and SATA 6.0 Gb/s controllers, while those with two cards must live with 2.5 Gb/s bandwidth limits on USB 3.0 and SATA 6.0 Gb/s controllers. Neither of these sacrifices is huge or even noticeable on most of today’s hardware, yet anyone trying to future-proof their system could be left cold.

Knowing that some users would rather pay more than sacrifice performance credentials, Gigabyte has been showing off its upcoming P55A-UD7 motherboard with PLX and nForce 200 PCIe bridges. The company has yet to announce the new product’s launch date or price.

Thomas Soderstrom
Thomas Soderstrom is a Senior Staff Editor at Tom's Hardware US. He tests and reviews cases, cooling, memory and motherboards.
  • Lessqqmorepewpew
    Great review. This waiting game sucks.
  • amnotanoobie
    Wow, transferring your por..... programs should be a lot faster now.
  • playerone
    This seems a bit dated, my two week old ASUS P6X58D Premium has Sata 6.0 and USB 3.0!
    Obviously waiting for a bit more mature drivers and more hardware...
  • Onyx2291
    Can't wait for it all to be standard.
  • staalkoppie
    Pitty they'll only be available at the back for now....but good news nevertheless
  • liquidsnake718
    BAH.... Im waiting for an X58 with USB.3.0 AND 16x 16x SLI. I would not want to sacrifice the other slot for a 8x config....
  • Crashman
    liquidsnake718BAH.... Im waiting for an X58 with USB.3.0 AND 16x 16x SLI. I would not want to sacrifice the other slot for a 8x config....
    Uh, d00d, 1366 CPU has 36 2.0 lanes, don't those X58 boards use the leftover four for USB3 and SATA6? I mean, c'mon, 16+16+4=36
  • bujuki
    I've been waiting to see how USB 3 performs. However, if you may it's better to test the CPU utilization comparison between all connectors as well. Still, thanks for the great review. b^^d
  • anamaniac
    Honestly, with USB 3.0, I don't see any reason at all for eSATA anymore.
    I just want a 80GB Intel x18-m with a USB 3.0 port. Who the hell wants a slow 64GB flash drive?

    I wish we could agree on a stanard already. I like USB, so let's just scrap IDE, SATA, eSATA, PCI (not PCIe), analog audio cables completely already. Well, that or miniDisplayPort.
  • JohnnyLucky
    Thanks for explaining how USB 3.0 fits into the grand scheme of things.