How can I determine the speed of my PCI Express interface ?

Try running GPU-Z. It will report the PCIE bus type and usage.

As for the original topic: You can use a USB3 external drive with USB2 ports. My mainboard doesn't have USB3 either. You will lose some speed though.

Thanks for the link, now downloaded and ready to use.

I have quite a few 8 GB Flash Drives with significantly different speeds.

The most recent is USB3 because I wanted to achieve speeds limited by the USB2 host and NOT be inferior Flash technology that could not achieve USB2 LIMITS.

so I considered it worth paying an extra 10% for whatever boost that could give at the time,

and also for use in the future (which is now scheduled for next week).

I was disappointed to find that the fastest of the USB2 flash drives was a few percent faster than this USB3

I am using a PCIE graphics card.

I will look into the availability of a non-express PCI USB3 interfact card.

Regards

Alan