James,
I just did this on my GTX 570 (the hack you posted) and though it’s not doing much, it is showing a 2% GPU usage as a render a mp4 file. Prior to your hack, it showed zero.
I have a 1 minute 1280×720 clip that I’m testing. I added some basic color correction to it, and running that through the Sony mp4 encode.
Before adding Vegas to the 3D settings, it was rending the clip at 5:19 and showing 0% GPU usage. Now it’s rendering the same clip at 4:10 showing 2% GPU usage.
The math doesn’t add up for me but it’s rendering a little faster.
I’ll also note that Vegas does not recognize CUDA regardless of my settings. But I did tell it to Render Using GPU If Available” even though it won’t detect the card in the system tab.
I just bought this card today and have been very disappointed with the rendering times in Vegas 10. I also have a GeForce9600M GT running in a Mac, on bootcap / XP, and it renders faster in Vegas than this new card. The ATI card I took out was faster too (by about 30 seconds per 1 minute of rendering time). Very disappointing. I feel like something isn’t working right somewhere. I’ve cleaned out all the old drivers, added new Nvidia, you name it. Nothing is helping.