Asus Turbocharges USB 3.0 With SCSI Technology

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Real-World File Copy Performance

We ran two sets of file copy tests to compare the various controllers and hard drives. Our initial data set -- a 2GB directory of mixed files -- was completely unaffected by any of the various settings. Once we swapped out our small files for a 26GB directory of encoded AVIs, we saw a moderate performance difference between normal BOT transfer and UASP/Turbo mode, at least in certain cases.

We ran each file copy multiple times, but rebooted the system between each iteration to prevent Windows' various optimization tricks from skewing the results. We also Secure Erased the drive between controllers to keep the SSD fresh. The "Intra" tests in this suite refer to copying files from one location to another on the drive.

Here's how the data breaks down. First up -- our Corsair Force 3 SSD and the Asmedia 1042 controller.

Activating UASP only improved our HDD - SSD copy speed by about four percent, but our intra-SSD copy time improved by nearly two minutes, or just over 15%. Since Asus sent over two compatible controllers (its own Boost Cable and a Thermaltake), we added a Corsair F120 SSD to the mix and did a USB-to-USB copy across the Asmedia controller. While UASP was enabled on both devices, performance was essentially identical. This is likely because the single XHCI controller in the Asmedia 1042 had its hands full moving data across the bus.

Since this test wasn't particularly illuminative, we dropped it for the HDD comparison. Here's the VelociRaptor and Caviar green breakout, again on the Asmedia 1042.

Again, the straight data copy shows only a small performance increase on the VelociRaptor. The caviar Green, again, is too slow to benefit from the better protocol's advantages. The intra-drive copy is where we see the SCSI protocol shine; even the mechanical VR drive improves its performance by roughly 10%. The Western Digital Caviar Green, in contrast, falls flat.

Did you notice that the WD VR drive is actually faster than the Force 3 in both the initial data copy and the intra-drive copy? So did we. It may be related to the asynchronous nature of the SSD's Flash; asynchronous dives transmit and receive data according to a timed pulse rather than on the rising and falling edges of their clock.

Here's the Intel controller's before-and-after when using the Corsair SSD.

Using Turbo Mode improves the data copy time by about 10%, roughly the same boost we saw from the Western Digital VelociRaptor. Comparing the two controllers, we see that Intel has a slight advantage over Asmedia in Normal Mode, with the ASM 1042 eking out a small win over Intel in UASP vs. Turbo.

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