Creating app_info.xml

You don't need the app_info.xml mechanism just to run a different GPU task concurrency on different machines. You have two particular much easier choices.

1. Put the hosts in question in different 'venues' (default, home, school, work) where you can independently set the appropriate GPU utilization factor to achieve the required concurrency. This is limited to a maximum of 4 different sets of preferences so should be quite satisfactory for you with four hosts in your computer list. If two machines need the same settings you wouldn't need the full 4 venues.

2. For control on a 'per machine' basis, the file you need is called app_config.xml. Scroll down to the bottom of this page, looking for the "Application Configuration" heading. Using app_config.xml overrides the web site preference setting for GPU utilization factor. By looking at your hosts, I'm assuming that you want to stop running 3x for the host with the GTX650? You could use the following app_config.xml file just for that machine to try 2x rather than 3x without having to change anything else.

  
    einsteinbinary_BRP6
    2
    
      0.50
      0.20
    
  

I notice that you are getting all checked results as 'invalid' on that host. I'm running both 2x and 3x on quite a few GTX650s and I'm not seeing invalids like this. My GPUs are well ventilated (completely open) and I can easily see any evidence of fluff buildup on the heat sink. That (and a free spinning fan) would be the first thing I would suggest checking, if dropping the concurrency doesn't work. You should also be monitoring GPU temperature if you are not already doing so. In the past, I've had success in lowering GPU temperature by removing the heat sink and replacing the 'rather dried out' thermal interface material I always seem to find :-).