performance of totally random access

What will be the performance of totally random access?
I do the experiment but the performance is less than 1gpbs.
Is it right performance? do you have any Idea?
FYI, my GPU is GTX 580.

See my benchmark here, it’s not completely total but it’s a pretty good indication:

http://www.skybuck.org/CUDA/RAMTest/version%200.10/

Post results here… ;)