gpu not recognised

[groggin]

  long story short:  i've an asus hd raedon 5670 + an r9-280x in a box under linuxmint, had the 5670 for a while, the r9 is new. i multiboot w win7 and xp

  prior to installing the r9, the asus is reliable @ ~88 khps in both win and lin
added the r9,  had both working well in linuxmint, later set it up in win 7 too, everything working ok.
on next reboot to linuxmint, the 5670 is not recognized, there is an error message about open cl and devices, and a warning they do not match, then cgminer continues w/only the r9 as cpu 0
later i try adding to the startup string:

Code:

--gpu-map 1:0,2:1

and some other variables, but it is no help.  ideas???
meanwhile, if i reboot to win7, everything is groovy w/2GPUs

[groggin]

 any ideas would be appreciated, haw can i get linuxmint to see the 5670?