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This quick benchmark sets forth to prove that SATA III and SATA II cables have no impact on data throughput. Note well that we are strictly talking about cables. The interface itself, obviously, has profound impact on performance – SATA II performs at 3 gigabits per second (375MB/s) and SATA III performs at 6Gbps (750MB/s). There is substantial overhead on the interface, so the actual operating limitation is closer to 550MB/s for high-end SSDs.

Test Methodology

This test is fairly trivial compared to our other in-house SSD testing. We took the fastest SATA drive available on our bench, Samsung's 850 Pro, and connected it to a variety of SATA cables from several generations of hardware. Anvil's SSD benchmark was deployed for rapid throughput measurement with each of the cables, then logged for comparison. The expected result is that all cables offer effectively identical performance, within a 5% margin of error.

The cables tested include Serial ATA cables that shipped with motherboards deployed with the very first version of the interface, scaling up through cables shipped with SATA II and SATA III equipped motherboards. The cables are of varying lengths – one is even significantly thinner than its counterparts – and shipped with different SATA version branding. If the branding is to be believed, a newer “SATA III 6Gbps cable” would be faster than our red “Serial ATA I” cables.

Some of the cables we purchased or acquired were branded as "premium" cables, with specific, clear branding as offering SATA I & SATA II compatibility (no mention of SATA III). Other, more modern cables were listed as "SATA III with backwards compatibility for 3Gbps and 1.5Gbps." A cable we purchased from Monoprice was explicitly branded as a SATA I cable, stating that it was "certified for 1.5Gbps speeds."

Let's get on with this:

SATA I vs. SATA II vs. SATA III Cables - Is there a Speed Difference? (No!)

The results are effectively identical. There is no measurable difference between differently-branded SATA cables as we tested. In doing further research, we found that Maximum PC was able to trigger poor cable performance by chaining ten feet of cabling together – not exactly an intended use case. The crazy part is that some of the cables we tested are $12, yet perform identically to a $0.57 cable. There is no performance difference. There may be a slight build quality difference in connection cycle endurance, but the speeds are the same, and no $12 cable will be noticeably better than, say, a $5 cable. StarTech is one of the companies selling $12 cables.

It's worth stating again that we are not testing the SATA interface's speed variation, as there's effectively a 2x difference between SATA II and SATA III as an interface. This is strictly looking at cables, like these.

There is exactly one reason that manufacturers sell SATA cables with “6Gbps” and “SATA III” branding in the product name: Buyers don't know there's no performance difference and think it is a requirement to use the SATA III interface.

You could buy a SATA cable for $0.53 and it would perform effectively identically to an expensive “SATA III cable.” Now, it might not hold-up as long or survive as many connection cycles, but the performance will be effectively identical.

- Steve “Lelldorianx” Burke.