I recently picked up an SSD and enclosure with a built in USB Cable. CrystalDiskMark shows a >500MB/s read speed and >400MB/s write speed with a direct USB C connection to a USB 3.1 gen 2 port, so all good here.

But I also picked up these adaptors from amazon.co.uk to ensure I could connect the drive to more common USB type A ports. These adapters noted that they could handle the 10Gbit speeds of USB 3.1 gen 2, although they do note that when this is the case the "other side" (Type A side) runs at USB 2 speeds. Out of a lack of options I decided to give them a go nonetheless and the claim is true. But it's not as simple as saying "these must really just be USB 2 adaptors with a blue finish".

When using the adapter to connect the drive to a front panel USB 3.1 gen 1 port connected to the USB 3 motherboard header, the speeds are ~300MB/s and 400MB/s read and write respectively. So the adapter can handle high throughput but just can't when used in gen 1 or 2 ports on the IO panel of the motherboard itself. Maybe this is a motherboard issue...

Edit: Just verified this across 2 Desktop systems:

  • Rear Motherboard IO (USB 3.1 gen 1 and gen 2) with adapter: ~40BM/s R/W

  • Rear Motherboard USB C with no adapter ~500MB/s R and ~400MB/s W (full speed)

  • Front panel IO connected to motherboard USB 3 header (gen 1) with adapter ~200MB/s R ~400MB/s W

What am I missing here? I have found only one adapter available that clearly states it has 10Gbit ports at either end but it's pricey so any alternative suggestions are welcome. Notably, it has a significant rectangle shape at the USB C side, maybe this is part of the explanation...? See below:

enter image description here

  • I thought "USB 3.0" and "USB 3.1 Gen1" were the same thing? – user1686 Jun 4 '18 at 16:22
  • That is true, I should probably rephrase my question for clarity. The USB 3.0 ports mentioned here are front panel ports connected to the USB 3 header in the motherboard, whereas the 3.1s are part of the motherboard IO at the rear of the case. – Sam3000 Jun 4 '18 at 16:32
  • Please name the motherboard’s make and model. – Daniel B Jun 4 '18 at 17:17
  • So, after trying to make sense of the product description, I think I finally got it (though it doesn’t make a lot of sense): When the host is connected to the adapter on the USB-C side, it supports only USB 2.0 speeds, for whatever reason. It’s not “the other side” but “the other way/direction”. – Daniel B Jun 4 '18 at 17:24
  • 1
    "while the other side runs at USB 2 speeds" - This means the adapter runs at USB 2.0 speeds. USB 2.0 isn't capable of 10 Gbit speeds and the connector is USB 3.0. The accuracy of products listed on Amazon is the responsibility of the seller. – Ramhound Jun 4 '18 at 17:48

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