My problem was solved.

I was set GPU device from Octane engine n its automatic saved with engine as default settings.

thanx for all.
especially Octane render team n Lionel Zamouth for exporter

@ matej : thanx, i'll post in blender community too.

Hi,

I have installed octane exporter in my blender 2.56a. I have problem to entry multi GPU device in octan system settings (in blender exporter)?

this detected device in active cuda device in my engine :
GeForce 8400 GS (1 compute 11 display)
GeForce GTX 460 (0 compute 21)
GeForce GTX 460 (2 ...