I have checked a little bit with the different settings that are possible for Cuda-Cards and ran:

dnetc518-win32-x86-cuda31.exe -bench

This brings up following:

dnetc v2.9109-518-GTR-10092921 for CUDA 3.1 on Win32 (WindowsNT 6.2).
Please provide the *entire* version descriptor when submitting bug reports.
The distributed.net bug report pages are at http://bugs.distributed.net/

[Jun 21 14:10:25 UTC] nvcuda.dll Version: 31.0.15.5176
[Jun 21 14:10:25 UTC] RC5-72: using core #0 (CUDA 1-pipe 64-thd).
[Jun 21 14:10:26 UTC] RC5-72: Benchmark for core #0 (CUDA 1-pipe 64-thd)
                      0.00:00:00.54 [10,041,063,384 keys/sec]
[Jun 21 14:10:26 UTC] RC5-72: using core #1 (CUDA 1-pipe 128-thd).
[Jun 21 14:10:27 UTC] RC5-72: Benchmark for core #1 (CUDA 1-pipe 128-thd)
                      0.00:00:00.46 [10,574,494,120 keys/sec]
[Jun 21 14:10:27 UTC] RC5-72: using core #2 (CUDA 1-pipe 256-thd).
[Jun 21 14:10:28 UTC] RC5-72: Benchmark for core #2 (CUDA 1-pipe 256-thd)
                      0.00:00:00.48 [11,201,033,720 keys/sec]
[Jun 21 14:10:28 UTC] RC5-72 benchmark summary :
                      Default core : #0 (CUDA 1-pipe 64-thd)
                      Fastest core : #1 (CUDA 1-pipe 128-thd)
[Jun 21 14:10:28 UTC] Core #1 is significantly faster than the default core.
                      The GPU core selection has been made as a tradeoff be ...
                      and responsiveness of the graphical desktop.
                      Please file a bug report along with the output of -cp ...
                      only if the the faster core selection does not degrad ...

The Automatic-Mode chooses Core 0 to run and the WUs take 345 seconds

When I manually change the setting to use Core 1, the WU needs only 312 seconds and I didn't check Core 2 so far.

Seems as if the Automatic-Settings needs some tuning.

Or can I set this local on each machines ? I have more different Cards then there are different profiles possible

There are 12 different CUDA cores, you should run the complete benchmark on each of your cards and than it might be enough to use the four different venues (default/home/work/school) to assign all of them the best cores, your cards are just from 3 different generations. The cores with lower numbers are for old cards, I guess the 2-pipe or 4-pipe cores should perform best (either #5 or #8 in particular, but that's just a guess).

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