USB 3.1 Tested: Performance On MSI's X99A Gaming 9 ACK

Results: USB 3.1 Vs. USB 3.0


We’ll start with synthetics, since that was what everyone at CES saw.

USB 3.1 enables sequential reads in excess of 700MB/s, and we’re told that a couple of Samsung 840 Pros crest 800MB/s plugged in to the same developer board. Intel’s X99 chipset manages 423MB/s, while VIA’s PCI Express-connected controller can’t even muster 300MB/s.

Write performance isn’t far behind (though we’ll see real-world sequential writes fall off faster). ASMedia’s USB 3.1 controller continues to exceed 700MB/s. Intel’s PCH-based logic actually accelerates, hitting 426MB/ and the VIA VL805 tops out at 257MB/s.

Random I/O isn’t nearly as impressive. But that’s what we’d expect from USB (or any other interface, for that matter). You’ll see reads approaching 7400 IOPS in 4KB reads at a queue depth of one from USB 3.1, while Intel’s controller yields over 5400 IOPS. This is one discipline where VIA comes out ahead of Intel; the VL805 posts nearly 6800 IOPS.

Real-World File Copy

Synthetic metrics work well if you want to isolate a specific performance attribute or test a peak using controlled data. But they rarely correlate with real-world results. That’s why we’re also including a real-world file copy test that includes 91 files in 27 folders totaling 36.7GB. Clearly, these transfers are going to be sequential in nature.

Reading data from the USB-attached RAID array and writing to a 40GB RAM disk on our PC yields much higher performance than writing to the external SSDs. ASMedia’s USB 3.1 controller gets the job done in an even 60 seconds. Intel’s built-in USB 3.0 logic finishes in 100 seconds. And VIA’s VL805—a single-lane PCIe to four-port USB 3.0 controller—turns out to be quite a bit slower at 145 seconds.

Coming back the other way, moving data onto the dual-SSD requires more time. The task takes 76 seconds via USB 3.1 on a two-lane PCIe interface. Intel’s own USB 3.0 controller posts a 113-second time, while VIA’s controller is outclassed at 173 seconds.

Sometimes enthusiasts get caught making a big deal out of relatively minor differences, but when you’re talking about a more than 2x speed-up compared to another third-party controller, that’s truly significant.