PCIe 1x slot only has 1gb/s (500mb/s each way) of bandwidth on a motherboard with PCIe 2.0, on 1.0 and 1.1 its half that... so dont get your hopes up to get the 5gb/s thats being advertised

@ mikefletcher85- Thanks for your input.

@Trollsprinkler- Thanks for your sarcasm.

@phoshzzle- Thanks for your stupidity.

#1's point is fairly irrelevant for two reasons.

1) 5Gbps is gigaBIT, actually 4.8 so that's 600MBytes/s on paper... just as 480Mbits/s for USB2 is only on paper - actual, real world throughput is below the PCIe 1X bottleneck.

2) You can't buy anything that exceeds 400MB/s throughput and uses USB3. Maybe someday, but why would you pay hundreds for such a device that uses the cheaper, slower USB3 bus? Maybe on a thumbdrive only so you have backwards compatibility with legacy systems.

I take back part of #2, limited cache transfers from a current or future generation external USB3 connected SATA HDD or SSD could peak above 400MB/s, but you'd only notice the difference on select synthetic benchmarks.

Bottom line - if you could get a PCIe 4X USB3 card it would be a waste of the 4X slot on it if you also had a 1X slot alternative, unless you were trying to do something wierd like make a high traffic fileserver out of multiple drive volumes connected by USB3, and of course your card had more than two USB3 ports on it or they were plugged into a USB3 hub daisey chained to it.

The real question is would this card offer significant improvement over USB2 to justify the twenty-something price and the answer is yes, we are at the point where lots of devices saturate USB2.

@mdheinzer- Thanks for nothing.