Running vantage at extreme preset. Will update soon. Tests at 3600/4000/4400 with 900 core. Posting from phone now.
EDIT:
3dmark vantage extreme preset physx on
900c/3600m: X8507
900c/4000m: X8667
900c/4400m: X8798
940c/4000m: X9049
Seems like it scales a little, not as much as one might expect though given the enormous boosts. I'm going to run a quick 940c/4000m and see what happens... then I'm done for the night . EDIT: Added result, seems core speed has a bigger effect on the GPU performance for sure in a (GPU-bound?) test here. Good info to know...
EDIT2: 920c/4200m: X8940