If I remember correctly 5.5 only had limited CUDA support so no OpenCL at all. You’ll need to use a later Premiere if you wan’t to use GPU accelerated effects. CUDA is Nvidia only.
[Alec Eagon] “I am in the habit of not upgrading things”
Hardware and software manufacturers are. CS 5.5 is 7 years old and basically dead in development sense. It won’t support any latest stuff.
[Alec Eagon] “Oh, one other note, my iMac is labeled a Quad-Core, but when I open the CPU in Premiere it shows 8 Cores….?”
It’s a quadcore with hyperthreading. Every actual core can be virtually split so you’ll have more cores more multithreaded applications.