After I max out the GPU clock rate, deviceQuery shows very low clock rates:
./deviceQuery/deviceQuery Starting...
CUDA Device Query (Runtime API) version (CUDART static linking)
Detected 1 CUDA Capable device(s)
Device 0: "GM20B"
CUDA Driver Version / Runtime Version 7.0 / 7.0
CUDA Capability Major/Minor version number: 5.3
Total amount of global memory: 3854 MBytes (4040933376 bytes)
( 2) Multiprocessors, (128) CUDA Cores/MP: 256 CUDA Cores
GPU Max Clock rate: 72 MHz (0.07 GHz)
Memory Clock rate: 13 Mhz
/sys/kernel/debug/clock/override.gbus/rate:998400000
/sys/kernel/debug/clock/override.gbus/max:998400000
/sys/kernel/debug/clock/override.emc/rate:1600000000
/sys/kernel/debug/clock/override.emc/max:1600000000
/sys/kernel/debug/clock/gbus/rate:998400000
/sys/kernel/debug/clock/gbus/max:998400000
/sys/kernel/debug/clock/emc/rate:1600000000
/sys/kernel/debug/clock/emc/max:1600000000