This app_info doesn't end in computation error:

<app_info>
<app>
<name>hcc1</name>
<user_friendly_name>Help Conquer Cancer</user_friendly_name>
</app>
<file_info>
<name>wcg_hcc1_img_6.56_windows_intelx86__nvidia_hcc1</name>
<executable/>
</file_info>
<file_info>
<name>hcckernel.cl.6.56</name>
</file_info>
<app_version>
<app_name>hcc1</app_name>
<version_num>656</version_num>
<platform>windows_intelx86</platform>
<plan_class>nvidia_hcc1</plan_class>
<avg_ncpus>1.0</avg_ncpus>
<max_ncpus>1.0</max_ncpus>
<flops>15867524679.495871</flops>
<coproc>
<type>NVIDIA</type>
<count>0.500000</count>
<cmdline>--gpu-target-frequency 60 --gpu-polling-mode 16 --gpu-disable-checkpointing</cmdline>
</coproc>
<file_ref>
<file_name>wcg_hcc1_img_6.56_windows_intelx86__nvidia_hcc1</file_name>
<main_program/>
</file_ref>
<file_ref>
<file_name>hcckernel.cl.6.56</file_name>
<open_name>hcckernel.cl</open_name>
</file_ref>
</app_version>
</app_info>


Whether the cmdline options are working is hard to say for me, because I'm not really suffering from the screen lag. Only a bit when using VNC Viewer to control another PC.
You suffers more, it seems, so you are the right person to test the frequency and polling numbers.

I was aware of the other position within the app_info, but because of the computation error, I tried it within the coproc-part. Not illogical because the params had to do with the co-processing GPU.
It was working, but I could not notice a difference.

I think that the conclusion is that those cmdline parameters are not supported by the WCG science application and are project/science specific.

Thanks for the confirmation, armstrdj, that command line arguments in an anonymous platform app_info.xml file, cannot be used as a workaround for this problem.
In the meantime, I continue to use my workaround -- when I sit at my computer, I select all "Help Conquer Cancer 6.56 (nvidia_hcc1)" tasks, and click Suspend. Then, when I'm about to leave my computer, I select them again, and click Resume.

I hope a solution is being worked on. I'm available for any testing assistance.
- Jacob Klein

If you're asking about including the <cmdline> line for this project...
- If you don't need to use an anonymous platform app_info.xml file to achieve your goals, then don't use the file.
- If you need to use app_info.xml, and you put the <cmdline> line after <coproc> but before </coproc>, it appears to be completely ignored, as its position is invalid, per documentation here: http://boinc.berkeley.edu/wiki/Anonymous_platform
- If you need to use app_info.xml, and you put the <cmdline> line after the </coproc>, then its position in the file is now valid (so BOINC uses it), but the arguments are invalid (the application says "invalid command line arguments"), and your WCG HCC tasks will error out (ie: it is bad)
- Long story short: If you need to use app_info.xml, I recommend not including a <cmdline> line at all, for this project.

Good luck,
Jacob

GPU Help, 11th topic from the top: http://www.worldcommunitygrid.org/help/viewTopic.do?shortName=GPU

What if my computer stutters while World Community Grid is utilizing my graphics card?
http://www.worldcommunitygrid.org/help/viewTopic.do?shortName=GPU#617

The root cause has been explained by the techs, in this thread no less! http://www.worldcommunitygrid.org/forums/wcg/viewpostinthread?post=395454 The kernels are already shortest possible. Some will thus have to make a choice and use the available options to suspend HCC-GPU crunching when it interferes or suspend WCG when it does.