clock rate on my GTX680 is only 706 MHz is it broken?

I’ve just bought a new EVGA GTX680 and found that according to deviceQuery its GPU Clock rate is only 706 MHz. Isn’t it supposed to be 1000+ MHz? Did they send me a broken part? Help!!

You are getting the same issue as this reviewer:

It is a bug in the runtime, it will be fixed in the next CUDA release.
CUDA 4.2 is now officially out, it should be in the release notes.

Can’t find it in CUDA_Toolkit_Release_Notes.txt.

I wrote a simple benchmark to bench the clock rate:

__global__ void wait( long long int *a, int n )


    long long int c0 = clock64(), c1;

    while( (c1 = clock64() - c0) < n );

    *a = c1;


It doesn’t do anything but waits for n cycles. I run it with 1 thread and a large n, measure its runtime and get 1.23 GHz. Now I wonder if it is overclocked ;)

Also I benched SGEMM - got 1.3 Tflop/s so far (‘N’,‘T’ case). Not much compared to the declared 3 Tflop/s peak. Is this what I’m supposed to get?

The official 4.2 release was posted yesterday ( but it seems no notice was sent to developers).
NVIDIA CUDA Toolkit v4.2 Release Notes Errata

Known Issues

  • Functions cudaGetDeviceProperties, cuDeviceGetProperties, and
    cuDeviceGetAttribute may return the incorrect clock frequency for the SM clock
    on Kepler GPUs. [Windows and Linux]

1.3 TFlops seems in the right ballpark.

Just realized it could be the new dynamic clocking feature a.k.a. “GPU Boost”. Can’t reproduce 1.23 GHz though. Now I get 1.123 GHz. I guess that was a typo ;)

That’s right - just checked it using EVGA Precision. It does adjust clock dynamically!

I get 324 MHz when nothing much happens on screen, 1005 MHz when some activity and 1123 MHz when running CUDA. Memory clock also jumps up and down, but it doesn’t seem to depend on the memory intensity of the kernel.