Coolbits with multiple GPU

I want to change the memory clock of my card to determine if my app is memory bound.
I saw we have to enable Coolbits in /etc/X11/xorg.conf so that a line “clock frequencies” appear in nvidia settings. The problem is I have several GPU, a 8500 GT attached to display and a GTX280 for cuda computation; and after enabling coolbits nvidia settings only allow me to change the clock of my 8500GT attached to the display and not the gtx 280. Is there a special option in xorg.conf to allow to change the clock of the other card?

Coolbits is an X driver option.

Ah, that’s what i feared. Thanks for the answer.