This isn't a GPU Grid issue per-se, but a GPU issue (it happens in Einstein@Home too). Recently, my GT240 started acting up; I set the preference to "run when GPU is not in use (1 minute delay)," and I see it starting and stopping.

I wait overnight, and when I check in the morning, it's not running.

I didn't change BOINC or my drivers recently, although a while ago, I down-graded my drivers since the latest ones caused my PC to be extremely choppy while BOINC is running. (The old ones ran fine with my GPU at 100% while I'm doing other stuff.)

What might the problem be? How can I diagnose and fix it?

Note: if I set my GPU settings to "Run GPU always," this makes the GPU start again. But it majorly chops my PC.

I'm not even sure what I would look for in terms of frequencies or downclocking. If my system is unusable, then I have no choice except to run the GPU only when the PC is not in use. If it depends on the task, I don't think that this will be solvable.

But I'm skeptical, because I was running GPUGRID for months without any of these problems. I tried all the old drivers, and none of them work without chopping anymore.

What's strange is that if I set GPU usage to always, my PC works fine. But once it goes into the state of very low GPU usage, that's when it really chops up.

Got it. The clock speed is downgrading from 549 to 135. How do I prevent this? This is not because of temperature; the temperature holds steady at 90C.

Okay, I'll try that. I had also set the texture filtering quality to "high performance"; not sure if that will do anything, but it's worth a shot, I guess.

None of the versions worked for me; they all downclock. I guess I'm stuck. I'll try Riva Tuner when I get a chance. Thanks for all your help!

The solution was, very strangely, to change my PC power settings to "always on" and disable my screensaver. This is documented on my SuperUser question here.