Bitcoin Mining Rig - Graphiccard GPU/MEM Core

Hi,

i have been using the tutorial for a headless linux btc mining machine. thanks for that to dukejer :-)
i am using 3x ati radeon 5850 and my problem ist that they only run at 550MHz GPU
when i stop all off them and start only gpu0 i got 750mhz. When i start gpu1 the frequency on gpu0 changes to 550 and the gpu1 is 550mhz. this continous with gpu2. after a while all gpu's are at 550mhz. i only get 220MHash/s on each gpu and usually they are supposed to be at 330MHash/s.
aticonfig --odgc shows me this atm.

Default Adapter - ATI Radeon HD 5800 Series
   Core (MHz) Memory (MHz)
   Current Clocks : 550 900
   Current Peak : 775 900
  Configurable Peak Range : [550-775] [900-1125]
   GPU load : 100%

this is the same on all gpu's
the peak is atm at 775 but he is not using it. i am also using the usual AOD peak range.

I am using this settings:
phatk VECTORS BFI_INT FASTLOOP=false AGGRESSION=13 WORKSIZE=128

greets

PhilAd