Discrete Graphics SLOW over Thunderbolt with Virtu MVP

[Marshall Robin]

I just finished the following build:

http://pcpartpicker.com/b/hXWXsY

Currently I have the machine hooked up to the thunderbolt port on an Apple Thunderbolt Display. I am running Virtu MVP so the discrete GTX 980 can output to the monitor via the integrated graphics. Motherboard and graphics drivers have been updated to current revisions.

When running the Valley benchmark, I get about 40fps in this config (ultra, 2560x1440, no AA). CPU and GPU never cross 50% utilization, and the Intel iGraphics never crosses 20%.
If I hook an old 1280x1024 directly to the GTX 980 and disable Virtu MVP, the benchmark gets about 150fps which is more in the right neighborhood.

Has anyone here tried to set up a system like this and encountered a similar drop in performance? From reading various posts around the internet and YouTube videos I had expected a drop in performance around 8%, not 70%.

Any ideas what could be causing it?

 

[RCguitarist]

Turn off Virtu MVP and plug straight into the gpu. Use an adapter if you need to. Virtu MVP is garbage.

 

[Marshall Robin]

Turn off Virtu MVP and plug straight into the gpu. Use an adapter if you need to. Virtu MVP is garbage.

Do you happen to know of a DVI output to Thunderbolt input adapter? I can't find anything of the sort.