Elitebook 8560w GPU throttling when on battery

Hi, all. I have Elitebook 8560w LG662EA (Core i7-2630qm, Quadro 2000m, BIOS F.20, Dreamcolor display), and I noticed recently that GPU is lowering its frequency considerably when running on battery. Have any of you experienced this with your 8560w's?

When switching from AC power to battery GPU clocks immediately drop to less than 50% and it leads to massive drop in GPU performance.
This doesn't seem to depend on any Nvidia Control Panel settings, Windows 7 power management settings or HP Power Assistant, or BIOS settings.
While this is good for battery life as it drops power consumption, there can be situations when performance is more important.

UPDATE: added some more numbers for battery/AC power to demo drop in performance
Power consumption results are from HP Power Assistant, CPU temps, GPU temps/clocks from NVIDIA System Monitor,
PCIe info and GPU PPP (Peak Processing Perfomance) from SiSoftware Sandra Lite, CPU clocks from HWINFO64.
NVIDIA Control Panel power management is set to "prefer maximum performance mode",
it didn't change GPU clock limit on battery.

Display was set to 60% brightness, Win7 "Maximum Performance" power mode with default settings
Both primary 75Wh battery and secondary 100Wh HP BB09 battery are connected for this test.
fluidsGL and bandwidth tests are from NVIDIA CUDA SDK examples.

While connected to AC power adapter:
Power consumption (fluidsGL): about 72-75W
Power consumption (idle): 55W
CPU Clock: All cores turbo boosing up to 2.8GHz constantly
GPU Clock: graphics 549MHz, memory 902, 1099 processor
GPU PPP: 422GFLOPS
PCIe x16: speed 5Gbps, max bandwith 7.8 GB/s
fluidsGL: 170 - 240 FPS
bandwidthTest: Host to Device/Device to Host Bandwidth - 2542.6/2471.2 MB/s

While on batteries:
Power consumption (fluidsGL): about 38W
Power consumption (idle): 20-35W
CPU Clock: drops to 800-1000MHz, no TurboBoost
GPU Clocks: graphics 202MHz, memory 324, processor 405
GPU PPP: 155.52GFLOPS
PCIe x16: speed 2.5Gbps, max bandwidth 3.9 GB/s
fluidsGL: 47 - 50 FPS
bandwidthTest: Host to Device/Device to Host Bandwidth - 1315.2/1318.3 MB/s

This drop in performance should be very noticeable in any GPU related task, games for example.

Temperatures for the above test were about 70C for CPU and 65C for GPU.

I also decided to kinda stress-test my 8560w to see how much power it would draw, while on AC power. Maximum power consumption that I managed to get
was 114W, all CPU cores at 2.6-2.8GHz TurboBoost frequencies, GPU usage was at 92-95% (normal clock freq. all the way), 100% screen brightness, CPU at 85C, and GPU at 71C.
You can replicate that situation by running OpenCL Median Filter example from CUDA SDK.
BTW, laptop stayed cool with these temps and comfortably warm above CPU/GPU,
and, after load drops to 0-5% for CPU and GPU, temps return to normal 60/55C within 1-2 minutes, if anyone is interested.

 

you need to turn off the 'adaptive' power saving profile in the nvidia control panel. Will stop it locking to lower end clocks.

i've not looked at the newer gen nvidia control panel in a while, but you should still have this feature.

Sio

 

yes, I know about this option, it is set to "prefer maximum performance mode". But GPU still clocks down to 200 MHz and PCIe speed drops to 2.5Gbps (as reported by SiSoftware Sandra Lite). This setting doesn't seem to help. I've tried latest version of drivers from HP site and from Nvidia with no difference.

 

So, did no one else experienced any drop in GPU performance while on battery?

I understand that reducing max GPU clock on battery should increase battery run time and reduce its wear.
If this is indeed normal behavior for 8560w, than personally I'd prefer if it was possible to change this GPU clock policy,
in BIOS and through some official HP app preferably, to allow it to clock to max level on battery when I need it. There can be situations when performance is more important than running from battery for more that an hour, for example if I need to demo my app that uses CUDA or OpenCL to someone when switching to AC power is not an option.