By the way, mint 17.3 give me the possiblility to optimize software sources. And I have done it.
I have reverted to default choice .. bot nothing changed.
Nvididia-modprobe non found

Could you try :

apt-add-repository ppa:xorg-edgers/ppa -y
apt-get update

So if someonne can tell me why with the same operating system (linux mint 17.3 cinnamon 64 bit) I have machine in which I see nvidia-modprobe in repository and I can install it and some other not.
Difference is only GPU type, but are all Geforce.

Check your repository file in /etc/apt/sources.list

Now with the different driver it seems BOINC is having a problem finding the card. Strange it didn't have that problem before.

nvidia-modprobe is a simple setuid root utility which loads the NVIDIA kenel
module and creates the NVIDIA device files, to allow usage of the NVIDIA
driver by client applications that would otherwise not have sufficient
permission to load the module or create the device files on their own.

Probably the easiest way to determine if the card is responsible would be to swap the 560 with the 640. That way the same driver would work with the 640 and you probably wouldn't have to change any settings. It should work with a simple card swap. You can try the CUDA 60 App, but it probably won't help considering you're having the same problem with the OpenCL and CUDA 42 Apps.

Hmmm, seems all the results are Overflows, which is highly unlikely. Checking your recent MBv7 results also shows Overflows. That particular machine may have been a bad choice for the first tests. I would suggest stopping BOINC and replacing the CUDA 42 App with the CUDA 60 App and seeing if it is any better. As long as you just replace the file names in the app_info and leave the version number & plan class the same you won't have any trouble. There is an example of an older CUDA 60 app in the app_info.xml~ file you downloaded. Basically you just change the App names and library names to match the new Version 8 CUDA 60 App.

"When you switch from Stock to Anonymous platform the first thing the Server does is Delete ALL the Stock Apps and associated files from the setiathome.berkeley.edu folder. If you don't have another copy, you will have to track one down. After the Server deletes the files the first time, simply stop BOINC and paste the needed files back into the setiathome.berkeley.edu folder. They won't be deleted the second time."