deviceProperties - clockRate a constant value?

Accelerated Computing CUDA CUDA Programming and Performance
1

I have discovered that on my 8800GT that the clock rate it claims is 1512000 kHz.

The core clock is 600mhz and i assume it is supposed to be doubled for the shaders to 1.2Ghz?

I did a search and found a result for an 8800GTX that returned the same value of 1512000 Khz clockRate…

Is this a bug? Can anyone try to confirm?

Also will there be an addition to CUDA to return memory clock speed?

Thanks.

2

I can also confirm that I obtained the same result on a 8800 GT (1512000 kHz). Can anyone enlight us ? :D

EDIT: I also obtained strange results using CUDA’s deviceProperties on other chips.

Quadro FX 570 : Clock rate: 918000 kHz (Core clock: 460)

Quadro FX 1700: Clock rate: 918000 kHz (Core clock: 460)

Quadro FX 3700: Clock rate: 1242000 kHz (Core clock: 500)

Quadro FX 4600: Clock rate: 1188000 kHz (Core clock: 500)

3

The 8800 GT number looks to be close to correct:

http://www.nvidia.com/page/geforce_8800.html

The shader clocks are generally more than double the core clock. The number you quote for the 8800 GTX sounds wrong, unless that was an overclocked GTX. Our 8800 GTX cards return:

Clock rate: 1350000 kilohertz

which is the correct clock rate. Are you using CUDA 1.1?

4

Just FYI, the clock rates reported by the query may vary depending on whether power management has scaled back the GPU clock from the normal rate. I first noticed this with MacOS X, but it can also occur on Linux in some situations. Once the GPU “wakes up”, the reported clock rate reverts to the normal values… I presume that overclocking a card would similarly affect the reported clock values, but I haven’t bothered to do this experiment.

Cheers,
John Stone