For my new build the peripherals such as the optical drive are built into the desk while the computer itself resides in a cabinet some feet away. Most of the cabling to make this work has been pretty easy to find, but I'm stumped on this one. My SATA drive bay has 2 USB 3.1 ports and they are designed to attach to a header on the motherboard using a 20 or so pin rectangular connector. I need a 6 foot / 2 meter extension cable with a male one of those connectors on one end and a female on the other. What do I even search for on eBay?
Instead of an extension cable (which you likely won't find over 50cm long), get a standard USB3 motherboard header to PCI plate cable for the back of your PC like this one from Overclockers, and run a pair of USB3 leads to the drive bay.
You want search for USB 3.1 internal extension Cable. That said at 2 meter, you are at 2/3rds of the maximum length, so make sure you select a manufactured cable, for example, and not a ribbon or loose wire style extension, example. As IanW mentioned you probably won't find a cable long enough but you could always build your own. The site I used for examples images, sells USB 3 wire and connectors. If soldering a cable isn't up you street, I know I won't want to try, then there are several mod websites that might be willing to make the cable for you. Alternatively I know StarTech sell 2 meter USB 3.0 A male to A female cables.
Ah, sweet, I think we have a winner! One of the places in the Google ads offers a 50 cm one, but says they can make other lengths.
So I contacted the place that advertised custom cables and they said "sure, just order 4 50 cm ones and leave a note saying you want it made as one cable". Yeah, except that the 50 cm cables are $20 apiece. I am NOT spending $80 on a USB cable! Not yet sure what the solution is, but it may well look like what IanW posted. USB 2 cables are 8 pin, aren't they? Any reason I couldn't make them out of Cat5 cable?