On 09/27/2016 11:55 AM, Always Learning wrote: > * in C6.5 (my install disk; OS be updated to C6.8) USB2 works but USB3 > does not. It is a bit confusing how you worded this. Are you saying that you have already installed 6.5 and fully updated it to 6.8? > Please does anyone have any ideas how to solve this baffling > time-consuming problem ? > > Is is a UEFI (motherboard Asrock 970A-G/3.1) configuration matter or > potentially the absence of a suitable USB3 driver for Centos ? You're probably not going to like my suggestion. Try CentOS 7.2 on this board and see what it finds. There comes a time in every EL release cycle where new hardware is no longer well-supported. CentOS 5 is way past that, and CentOS 6, while not as far past it is still too old to install on some of the newest hardware. Even CentOS 7 has issues with some of the newest hardware. You have the double-whammy of UEFI and a newer chipset. While CentOS 6.8 can handily support USB3 on some hardware (been there, done that myself, with CentOS 6.5 if I recall on a Dell Latitude D830 with an ExpressCard XHCI (USB3) controller that worked great). You can of course try the ELrepo kernel-lt or kernel-ml packages, which provide the LongTerm or MainLine kernels packaged for CentOS.