I had thought I had tested this USB 3.0 cable throughly when I received it from eBay last year but apparently not, as today I just found out that my USB 3.0 to gigabit ethernet on my MacBook 12" got only a measly 40MB/s read speed from my Clouds; without the cable, I got my 88MB/s reads. No idea how this cable got through my QA eBay acceptance test. I bought it just to allow my USB 3.0 ethernet adapter to sit a little further away from my notebook.
This isn’t the first time I found flawed USB 3.0 stuff on eBay/amazon as I think all of the USB 3.0 stuff are flawed. The USB 3.0 Hub I bought, the ports are painted blue but run at USB 2.0 speeds. This particular cable probably ran above the USB 2.0 speeds on a simple My Passport test thereby did not flag my senses that something was amiss.
Today I had to test my whole network to check that I am getting my gigabit speeds throughout and I was surprised that my MacBook 12" took such a long time to copy a movie. Signed on to my old Mac Mini and copied the same file to find, to my relief, that it was back to its old self of 10 seconds to read a 889MB file. Turned on my Gaming PC to find that it too was reading, according to its stats, at 120MB/s.
Only the Macbook was reading at a measly 40MB/s. After changing the ethernet cable, turning off Wifi and finally removing the USB 3.0 cable did I find the culprit.
Just thought I post up to warn those that do buy from eBay or amazon. I have also bought 50 feet cat 5e cables from eBay that are not cat 5e cables. Best to buy it from BestBuy where you can test and refund if they don’t carry your data at gigabit speeds; this is the same with the USB3.0 hubs and cables.