afaik the flag is called "-d" for device.
-d 0 for the first device, -d 1 for the second and so on.

--platform and -d are different commands completely.

-d tells the miner what hardware to use, and --platform tells it what software to use.

Hi.

I have Nvidia cards in addition to an ATI 5970 as well. I'm having problems getting the second core to mine. I'm using the option "New OpenCL miner" and selecting rpcminer-opencl.exe. I've used flags -platform 1 and tried -gpu and -d flags, but the software allways only loads one ATI core according to GPU-Z. If I run two instances with different -gpu or -d flags, the per client client hash rate gets halved.

Only Catalyst driver 11.3 works for me, the other ones I've tried give me OpenCL errors. Can anyone give me some advice on which driver versions and flag settings that work?

Thanks, but I found a solution by using Diablo miner. Diablo seems to use a flat OpenCL device enumeration, without a platform flag. In my case the 5970 cores are devices 5 and 6, whereas devices 1 to 4 are the cores of my two Nvidia GTX 590 cards. Combined hash rate is around 1 GHash/s.

And I can play with Quad SLI with the same system. Perfect 

The only minor problem I have is that I have to disable the ATI devices in Control Panel in order to use PhysX. But I guess this can be done by a script as well.