From May 2013 until last week I was using my PC (Intel Core i5-750, 8 GB RAM, RADEON 5700 with 1 GB memory, Windows 7 Ultimate) with no problems at all, running 24/7 with Boinc projects always loaded. Also GPU was ALWAYS utilised.
Utilisation of CPU was about 80 % (temperature about 45 C), and GPU 75 - 80 % (temp. about 55 C), while i was not doing any demanding tasks (only Boinc projects running). It worked great with no problems!
Few days ago it started to stutter while watching video, and then to stutter and slow down generaly while using computer for most trivial stuff , like opening folders, right clicking with mouse on desktop, etc....
If I suspend GPU in Boinc Manager, all problems are gone.
At lease for two to three weeks before this happened i didn't install any driver, or any piece of software of any kind.
I tried to disable AV, and disable at startup other programs that I use, then restart PC, but problem is still here.

Can anyone have any idea why is this happening only why GPU is used?

Thanx

What are your temperatures these days?
Have you ever cleaned out the dust-bunnies from the inside of the heatsinks and fans of your CPU and GPU?

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Temperatures are same as I mentioned in my post, CPU 45 C, and GPU 55 C, when loaded with Boinc Project. When idle, CPU about 22 - 24 C, GPU 40 - 42.
Heatsinks and fans are clean.

If you GPU utilization is pegged, you're bound to get some lag in the UI. You can use the "Use GPU while computer is in use?" preference to control that; I have most of my hosts set to a delay of 1 minute so GPU computing picks right up without causing any disturbance to the user. However, I may have to a manual GPU suspend if I'm watching Netflix or something like that.

You might also look at a slightly less demanding GPU project; for example, Moo! Wrapper seems to hover around 90-95% GPU utilization (and sometimes short periods of less activity) which allows me to keep the GPU running without lag on one of my hosts.

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My Detailed BOINC Stats

I have recently updated BOINC to 7.2.42. I am having the same problem with using the GPU. It has been running fine until this morning when trying to control the machine, the mouse lagged very far behind and made control very difficult. The computer is on 224/7. I run rosetta and poem@home. If GPU was in use on either of these the mouse was very difficult to use. Changed GPU use only when computer is not in use and problem is solved.

Changed GPU use only when computer is not in use and problem is solved.

Which is the default setting, just to make sure that BOINC isn't interfering with your normal use of the computer. Any other setting is something that the person behind the keyboard (and mouse) changed to.

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