USB 3.1 Performance Preview: ASUS Z97-A/USB 3.1 motherboard

Results - AS SSD Benchmark

AS SSD 1.7.4739 Results

AS SSD is a sequential benchmark that utilizes incompressible data for its tests. The results here mirror what we saw in CrystalDiskMark, where USB 3.1 (Turbo mode) posted sequential read/write transfer speeds over 750MB/s, only to have the lead narrowed down when it came to random read/write tests. The performance benefit of ASUS USB 3.1 Boost also disappeared when it came to performance in handling 64 files in parallel in the 4K read/write (64 Threads) test.

According to ASUS, its USB 3.1 Boost utility does not have the luxury of command queuing either as it relies on the ageing Bulk-Only Transfer (BOT) architecture, which can only handle one request at a time while waiting for the device handshake to complete before commencing with the next data transfer. As a result, it probably will not result in improved transfer performance for the simultaneous transfer of multiple files, which explains the lack of a significant difference between the transfer speeds of USB 3.1 in both Turbo and Normal mode in random read/write tests.

However, there is still an approximately 45% difference between USB 3.1 (Normal mode) and USB 3.0 in the 4K write (64 Threads) benchmark (as opposed to the 40% difference using USB 3.1 in Turbo mode), which can probably be attributed to the adoption of the SCSI protocol in USB 3.1. SCSI provides better data throughput than BOT because of its streaming architecture and better queuing and task management, which eliminates much of the round trip between command phases. The architecture is also better at multi-tasking, which further improves performance in instances where there are multiple transfers.