My setup had two Nvidia GPUs which ran with no problems. later I noticed that one of the card was running at a high temperature. I discovered that one of the fans was rubbing against its housing. I replaced that card with an ATI model. I installed the drivers and started BOINC. Two ATI tasks were downloaded. The ATI GPU started on the tasks but keep switching back and forth between the two tasks every minute or so. Is this normal or is there some setting I overlooked?

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Earl F. Parrish

By default a GPU runs one task at a time. When the GPU is switching between two tasks, it's because BOINC isn't sure it will be able to finish both tasks by their deadline. That can happen when you first run the tasks on the new GPU. BOINC doesn't know how long these tasks will take on that GPU and when its own internal calculations show they may be in deadline trouble, BOINC will try to finish both as soon as possible. Thus the switching.

That'll go away.
However, I see that you run your system to the max. Both the Nvidia and ATI GPU tasks use CPU, for transport and part calculations. It's always a good idea to keep at least one CPU free to help the GPU(s). In most cases it's even best to free one CPU per GPU.

To do so, go to your computation preferences, if you used the ones from the website, they're at https://setiathome.berkeley.edu/prefs.php?subset=global, while if you used the ones in BOINC Manager, they're at BOINC Manager->Options->Computing preferences->Computing. Mind, at the top of this screen it shows which preferences you use, the web or local preferences. This in case you don't know.

Now edit these preferences and change "Use at most 100% of the CPUs" to 88% (= 7 of the 8 processors) or to 75% (= 6 of the 8 processors). Save changes. When using the local preferences, these will be used immediately. When using the web preferences, these will be used after BOINC contacted the server. The freed CPU core(s) will now be used by the CPU to work better with the GPUs.

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