It’s not exactly a straightforward question to answer, but let me take a shot at it…
I haven’t been able to figure out how these new MacPros actually utilize both GPUs to their potential with only 1 CPU as that kind of reverses the ratio that’s been considered to be the most practical up until now…
That said, Premiere Pro will utilize the GPUs (OpenCL) during effects work, interpolation on decode, etc. After Effects will mostly utilize the OpenGL part of the GPUs, pretty much active in the pixel-draw process at the display.
If you’re working primarily with DSLR (H264) footage…I have found that CPU clock speed trumps core count for speed of encode/decode with H264 formats myself…
Based on the bit of info you’ve noted, I guess I might lean toward the faster clocked CPU, but I haven’t done any definitive testing on the MacPro GPUs and how they compare in Premiere Pro…most of the comparisons out there are simply utilizing benchmarking software, or games.
TimK,
Director, Consultant
Video Producer at I-CAR