Asus has quietly slipped in a new feature in a bunch of their more recent motherboards including the P8Z77-V and a few of its contemporary brethren, calling this feature “USB attached SCSI protocol”, or UASP if you find it to be a mouthful. According to Asus, UASP might nearly double the speed of USB 3.0 connections to external hard drives and SSDs, hence speeding up the transfer rate of older USB 2.0 connections, now how about that?
To put it simply, UASP throws on top a blanket of modernity to the USB transfer protocol. USB 2.0 and 3.0 at the moment still rely on the Bulk-Only Transport (BOT) protocol for mass storage I/O, which is a very simple (a nicer way of saying dumb) protocol that limits USB 2.0 to just 480Mbps, while USB 3.0 carries a maximum data rate of 4.8Gbps – hence pushing the limits of the BOT protocol, especially when one is moving 100s of MBs per second from an SSD or a VelociRaptor.
UASP will ditch BOT and have something similar to SCSI as a replacement, making it far more suitable for low-latency bulk data transfers. Hot Hardware did perform a benchmark, hitting 5% to 20% increase in speed boost compared to the 70% that Asus claims. Minimal? Well, at least is better than nothing, right?