There are some very odd things going on with my Mac 285 installed half an hour ago. It seems to have two speeds and I wondered if anyone knows how to control this. I am using the drivers released by Nvidia in the last day or two, which are better than the ones on the CD. I have been running the OpenGL Extensions viewer benchmark and also some CUDA timing examples. The first time I ran OpenGL I got rubbish results, then the card seemed to speed up and was much better. Similarly I ran the CUDA deviceQuery, and also the MonteCarlomultiGPU code and got two wildly differing numbers. For example, deviceQuery reports a clock rate of EITHER 0.6GHz OR 1.48Ghz, and the "options per second" reported by the MonteCarlo code differs by a factor of 10 (TEN!!!) Sorry if I am being dumb - but do we know if there is a sleep mode and how to keep the card awake. Screen dump below illustrates the issue. I ran the top code after hammering the card with OpenGL benchmark, then waited and ran the next one. Note the change from 1.48Ghz to 0.6GHz. The OpenGL scores are pretty good in awake mode. I am trying to compare the Mac version with an injected PC one and the results are rather confounded by the throttling.