Strange bug with Gtx 750ti

Hi guys, i just bought nvidia geforce 750ti graphics card, i have installed newest drivers 340.52 and CUDA Toolkit 6.5 . Now i’m developing application for image processing using EmguCV and C# and i want it to execute on GPU. Now when i install EmguCV and start some of Example apps like FaceDetection, on CPU it exectues in 500ms and on GPU it stuns for 3-5mins and than it executes. I have tried different versions of drivers with different versions of EmguCV library and the problem is always there… I also switched between windows 8.1 and win7 and nothing helps. Now i’ve tested examples on friends graphics cards gtx 780 and gtx 550 and everything works fine. So does anyone have any idea what to do or anyway that i can test if everything is ok with CUDA cores ?

Thanks in advance

we are also having the same problem.I am glad if anyone can help me out in this regard