HD Tach
We used HD Tach 3.01's 8MB zone test to measure basic SATA throughput and latency.

AMD has a slight edge in burst performance, managing 4MB/s faster than the 590 SLI.

That victory is short-lived, though. The 790FX is way behind in HD Tach's sustained write speed test, offering just over half the throughput of the 590 SLI.

AMD finds some salvation in HD Tach's random access time test, where the 790FX just edges out the 590 SLI.

The 790FX also exhibits lower CPU utilization, although to be fair, scores are within HD Tach's +/- 2% margin of error in this test.