FAH client is pushing the hardware limits
From FaHWiki
Pande Group travels further into more complex methods of protein calculations... This results in WUs that are larger in size to download, and that use more system memory. All this data must be processed by the CPU, and depending on the project, can have a varying impact on the system's overall performance. By default the FAH client will run normal WUs that should not have significant impact, but there are ways to get more demanding WUs that can bring your system to its knees.
It has been noticed that when the FAH client is set to run at 100%, some programs (especially games) appear to misbehave. This situation may be rectified by altering the CPU usage given to FAH.
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