Which NVIDIA graphics card is better use with the new Tesla K20?

Hi all, after a long time I can finally use a Tesla k20.
But I have some doubts about how to configure my PC.
I know that Tesla needs another Nvidia card and one of the best solutions could be a Quadro as specified here: http://nvidia.custhelp.com/app/answers/ detail/a_id/2144/kw/Tesla/related/1

I plan to use the Tesla for general purpose computing not directly related to the graphic. I mean, no immage processing or video processing (I don’t need the features of Quadro card).

So my questions are:
What happen to the performance of Tesla card if instead of a Quadro I use the cheapest GTX (Kepler)?
What happen to the performance of Tesla card if I use a Fermi GTX?

I hope someone can help me. Thanks.

The performance of the Tesla card will not be negatively impacted by the graphics card you use.
You should consider using one of the new GTX 7xx series - they have the same compute capabilities so that will help your development, especially when you do some multi-gpu development.

BTW if you haven’t already - you should become a CUDA Registered Developer and download the new CUDA 5.5 Release Candidate - there is a bunch of new features which help developers using the K20. You can find links to the CUDA 5.5 RC here:
https://developer.nvidia.com/cuda-toolkit

Good luck and let us know how you get on with your Tesla.