I have a 2 Gig CUDA card now in my system. I was going to also get a 4 GIG card however in the FAQ I read this
17) If I get 2 graphics cards, do I double the memory available?
No, the memory available will be the memory capacity of the smallest card in your system. If you have a 1Gb and a 2Gb card, and need over 1Gb of memory for your scene, turn off the 1Gb card in the Cuda Devices tab of the plugin.
My question (before I buy this 4 gig card and Octane) is can I put the 4 gig in the system and make sure Octane uses the 4 Gig or no matter what Octane is going to use that 2 Gig Card?