I'm running amd A10 apu's on three of my rigs and I am going to be installing amd r9 280x video cards on all three of them. Would I benefit or increase performance on the WU for the current project I'm running by joining both apu+r9 280x video card together or should I just use the amd r9 280x just by itself? Hope you guys can help answer this question. Thanks in advance.

The CPU and GPU wont't be working on the same tasks, so there is no "speedup" that you will see on any work by utilizing the GPU as well. However, the GPU will crunch tasks more efficiently than your CPU so you will see a higher credit output. You will also have to find a project that supports your particular GPU as they are not universally supported by the BOINC projects. One good tool to find whether a project supports your specific GPU model or not is WUprop (http://wuprop.boinc-af.org/results.py) which will tell you which projects other crunchers are successfully using their GPUs for.

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