I think it's highly unlikely to be "the task" which causes this, but more likely to be "the type of task". Try to gather information about which type of task is running when this happens.

Can you tell me how to gather info about which type of task is running? When I open BOINC manager and look at the tasks tab, the only info I could imagine of being any use is the name of the task. For instance the top 2 Einstein tasks on my gaming PC are named LATeah1077F_1368.0_136524_0.0_0 and LATeah1077F_1368.0_250666_0.0_0. Farther down the list I have projects that say h1_0647.45_O2C02CI4ln0__O2MDFS3a_Spotlight_648.10Hz_680_1. Does that tell you what type of task is running?

I was recently able to get my hands on a Ryzen 5800x for the gaming PC and so I upgraded the living room PC to the old 3700x. So the old-old Q9650 is retired for now. I'm sure you're all aware of how bad the GPU market is so I had to keep the GTX 560 Ti in the living room PC. When trying to run BOINC with this new setup, the "BOINC screensaver loading" icon appears and the screen will flash like it's trying to load then go back to the "BOINC screensaver loading" icon and do that in a loop until I move the mouse. I'm also running a different video driver this time, 388.xx loaded by Windows 10 instead of 391.xx from nVidia's website. What I did just so it would work in some capacity again was I went into the Windows screen saver settings and set "Run project screensaver" and "switch between projects" to "never". Then set "run BOINC screensaver" to 1 hour. Now it runs the BOINC screensaver where the logo fades in and out with a list of all the projects that are active. I can hear the CPU and GPU fans ramped up and hwinfo shows them getting hot so at least they're doing work again this way. The gaming PC is still running the Einstein project screensaver just fine.