Versions 7 of BOINC do not have a cc_config.xml installed file by default on a clean install. You have to create one if needed. If you upgraded from a version 6 to 7 then the old file from the version 6 would have been in the directory.

Just wondering, what is this part in your app_config file supposed to manage?

<app>
<name>hcc1</name>
<max_concurrent>8</max_concurrent>
<cpu_versions>
<cpu_usage>1</cpu_usage>
</cpu_versions>
</app>

I would recommend to delete it and keep only this part which is controlling the number of concurrent GPU tasks and the number of CPU threads for such stated number of tasks (ETA: i.e. 8 GPU WU's on 4 CPU threads in your case - sorry, too high maths for me ):

<app_config>
<app>
<name>hcc1</name>
<gpu_versions>
<gpu_usage>.5</gpu_usage>
<cpu_usage>.5</cpu_usage>
</gpu_versions>
</app>
</app_config>

Cheers

You can combine the whole in a single hcc1 section [avoiding lurking conflicts] and if you like to hard limit CEP2, whilst buffering more [I do, by setting web profile to a higher value, to ensure there's always a older CEP2 to jump ahead], add an additional section with max=2. Here's a sample of the whole fest:

<app_config>
<app>
<name>hcc1</name>
<max_concurrent>8</max_concurrent>
  <gpu_versions>
    <gpu_usage>.5</gpu_usage>
    <cpu_usage>.5</cpu_usage>
  </gpu_versions>
</app>
<app>
<name>cep2</name>
<max_concurrent>2</max_concurrent>
</app>
</app_config>

Think the 7770 can do lots more than 2 concurrent like <gpu_usage>.25</gpu_usage> running 8 on GPGPU in total reserving 4 CPU cores. Max concurrent for HCC would then be 10, so in total 6 cores are used, the 2 remaining left for CEP2. 'Experiment' continues to be the adage for maximized GPGPU resources [If you're interested].