Run CUDA-Z and post the screen shot like the above. My guess is that you will find the card running at PCIE 1.0 speeds of 2.5 GT/s. So while the card itself is running at normal speed, it's link to the CPU is running at half speed. (Same as running at 8 lanes instead of 16)
For most things, you will never notice a difference. But at high data transfer speeds this will matter. If you don't need the extra speed, no worries.
http://sourceforge.net/projects/cuda-z/files/cuda-z/Beta/CUDA-Z-0.6.133-SVN...
It's a simple little app, useful for diagnosing CUDA issues.
Coincidentally, today I am working on GTX570 with 2.5 GB and Displayport. Should allow boot screens and use of System disks on an Apple 27" etc when I am done.
Already have the PCIE 2 enabled
