Differences in Geforce and Quadro implementation - Custom Timing

Geforce Titan - Driver Version 340.52
Quadro K5000 - Driver Version 340.52

I was able to successfully build and run the CustomTiming sample code “as is” on both systems. However when I changed the custom resolution to 1024x2400 (sample code has 1024x999) I was able to successfully run it on the Quadro but it gave an error of -1 for NvAPI_DISP_GetTiming() when run on the GeForce.

On the GeForce I tried different override timings with limited success; NvAPI_DISP_GetTiming() would run successfully but then the NvAPI_DISP_TryCustomDisplay() would fail with a -5.

Any idea what the issue would be between the Quadro and GeForce?