I have crunched a number of some strange WUs. They take as much as 2-3 times to complete in comparison to regular ones (run time 54000 sec vs normal 16000) but they all given same credit. Is there any explanation for this? Here is a link to the computer.

2 x GTX260, 197.13 driver - clean install (with driver cleaner via safe mode), boinc 6.10.56.

I have one more task WU in pipeline that shows same pattern. It is running for 7 hours already and it is only 58% complete.

I've had

78-IBUCH_389sel_pYEEI_100610-0-20-RND3849
p29-IBUCH_0511_pYEEI_long_100505-22-40-RND0861

- the first on a 9800 GT over the weekend, and the second on a GTX 470 two weeks ago. Both took almost twice as long as normal, but did at least get roughly that extra in credits, too.

Dmitri Toubelis, Either your card has defaulted to some slow state or the computer was in use at the time. Leave a program open on the desktop.

Yes I think this is it. I had a screen saver enabled and even though it was just a default windows XP one it somehow managed to clock down the GPU to ~1/3 of it's normal speed. I figured it is nvidia's feature on GTX 2xx, but I wonder if someone figured out how to control it.

On one of my XP systems I have to leave EVGA Precision open to stop the card from going to sleep. I think this is driver related, and depends on the operating system. You can use NVidia Control Panel to set the card for speed, and on XP you can disable the screen saver and stop the system from turning off the display from the desktop properties configuration applet. On Win7 and Vista, you also need to make sure your Power Options are configured correctly; if you leave them at their default it can put the system to sleep if it is not used for a while.