Last week I upgraded to BOINC v6.10.18, x64 from some previous version. I'm not sure if the previous version was x86 or x64.

The SETI@Home project is the only one I'm running. After installation, I noticed my productivity had dropped precipitously -- about 40%. I then noticed that when the screen saver was running, I could see the project's calculations run for perhaps one second, pause for a bit less than one second, and then repeat ad infinitum.

Installing BOINC v6.10.18, x86 seems to have fixed this problem.

PC Description:
* Intel Core2 Duo E7200
* 6GB RAM
* ATI video card
* Windows 7 Home Premium with all current updates

Check the CPU time % and if your Activity menu option is set to Run Always or Run as per preferences. At 60%, you'd see with a duo such a throttled behavior.

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I have not made any changes to the CPU preferences in a very long time, if ever. This productivity change started with the installation of the x64 build. No other s/w installations had been made for several days prior.

I used to average about 400-600 credits/day; with x64, it was only 200-300 credits/day.

Under the Activity Menu:
* [Checked] Run based on preferences

Under the processor usage tab:
* [Checked] While computer is in use
* ...use at most 100% of the processors
* Use at most, 100% of CPU time

A bit of an update on the observed behavior since changing to x86:
* I no longer see the pause-start cycle on the screen saver.
* The statistics graph appears to show a continued downward trend (based on roughly 24 hours of computation time since x86 was installed.)

Really makes no sense as I run X64 bit client, albeit, due to a (what I perceive as a bug in the latest) at Run Always. Stab in the dark, the screensaver does not get replaced when installing the 64 bit client, but no idea if the 32 and 64 bit are identical for that part.

Maybe the SS under 64 bit eats CPU time itself. At WCG one can set the frames and CPU time allocated to the SS. Probably you could log in from a remote client and monitor the CPU time in the BM.

Did you ask over at the SETI forums as here I've not seen such an observation.

I did/have not posted over at SETI.

I thought you may be interested to see the impact from installing x64 and then the recovery after installing x86. Sorry it's not bigger, this board made it tiny, but you get the idea. The top of the Y-axis is 610, the bottom is 370.

Now that it's working, I'll probably just leave it alone.

Another view, nine days later. The Y-axis scale is unchanged. There would have been quicker and smoother progress except the SETI project had several days of equipment trouble which resulted in delayed uploading of results.

Clearly, there is a problem with the x64 implementation.

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I'm seeing the same thing in performance monitor. It happens on a specific interval.