Spirit_Rises
here is an update

i had another board gigabyte 990xa ud3 and tried the usb 3.0 bracket on it and it worked fine.all of the 2 ports on it worked fine.but as i said one of the ports still doesnt work on evga mobo.so something must be wrong with the usb 3.0 socket on evga mobo

 
Time for an RMA then!

This won't help your overcurrent shutdown.  Go into Device Manager in Windows and make that the check box for each USB hub that allows Windows to turn the power off for power management is unchecked.  That will stop some of the intermittent access problems for external devices. 
I've had the overcurrent issue shortly after upgrading to this MB even though all the devices I had worked fine on the X58 classified it replaced.  I replaced my external HD thinking there was a problem with it but no change.  I've lost count of the number of times I've reloaded the Asmedia and Marvell drivers.  I adapted by moving my external HD to my WIFI router which has no problem with the device.  I had to add a USB wifi for a connection this past month at a temporary residence and wound up shutting down all my USB ports when I tried to add a different USB HD (even though they were on separate USB hubs).  The BIOS shows no issue, and all USB devices would work until Windows loaded.  Windows 8.1/64 continues to be overly sensitive to current draw on the USB ports with the available drivers.  Marvell support is nonexistent and what I see from EVGA and the other users with this issue is mainly finger pointing.  The latest for me is EVGA Support saying the voltage variation in my PSU on the 12v is excessive, even though it is better than any of the test results seen in the PSU testing seen for the 80 Plus Gold standard - and those variations from the online testing were described as excellent.  Just the same, I just spent $$$ for a Platinum standard PSU to eliminate that excuse even though I could have gone with an ASUS or Gigabyte replacement MB for less.  There are some indications that this problem is carried over to the X99 series as well which indicates to me either a problem with the MB or the available firmware/drivers - my money is on the latter.  I haven't quite made up my mind to jump ship yet to another MB manuf, since I'm still hoping that EVGA will get their act together, but my patience/faith in EVGA's past support commitment is not unlimited.