I have just installed a spare graphics card in a windows 7 64bit, i5 system (named Tigger). I am getting severe lock ups every 5 seconds or so for about 2 seconds, & many of the work units are failing with various error codes.

Has anyone got any ideas about what to try?

(I would love to make time to investigate this but with a 3 year old lad & twins aged 8 weeks I don't have the time)

I had a 460+650ti in a system and once I got it set up right (both monitors had to be on one card) it worked just fine...
The only thing I can suggest is I would try a clean driver re-install.
Bob.

I had a 460+650ti in a system and once I got it set up right (both monitors had to be on one card) it worked just fine...
The only thing I can suggest is I would try a clean driver re-install.
Bob.

I also removed all projects then re-installed BOINC. Drastic, but I don't have much tinkering time.
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So far all I know is that it's not because of the two video cards - last night the repeated 2 second lock up reappeared with just the GTX660 fitted, & it stayed even after BOINC was shut down. Maybe it is not because of BOINC, but it only appears when BOINC is running.

confused.com
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Are you having a driver crash error and then the computer starts working again when the drivers recover?

I was having this problem with one of my 680 FTW+ cards back when I was running them. I was able to RMA it for a 770 FTW from EVGA and then it's co-680 as well since they were used in an SLI system. A Friend of mine is using the 770s now though.

Anyway, in my case it seemed almost like a voltage regulation issue on the card, as the drivers wouldn't seem to crash while it was loaded crunching for BOINC, just when it was idling or nearly idling.

For me, it turned out to be an issue with one of my 680s. I know it was the 680 since it's partner card wasn't suffering these issues, even when moved to the same PCIe slot.

Congratulations on your young ones (and my sympathy for the workload). Hope all is going well. My daughter is a bit over 7 months old now. It goes by quicker than I expected.
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My BOINC Cruncher, Minecraft Multiserver, Mobile Device Mainframe, and Home Entertainment System/Workstation: http://www.overclock.net/lists/display/view/id/4678036#

@Wrend,
When it goes wrong, everything is OK for about 4 seconds, then the screen including the mouse pointer freezes, and this repeats endlessly (work - freeze - work - freeze) until the PC is rebooted.
It is not the combination of using the 660 & the 460 that is the problem because about 2 weeks ago it did the same thing once with just the 660 in, so it could be the 660.
Since then both the 660 & the 460 have been running with no problems.
So that's that until it goes wrong again - wish I knew why it was working!

(7 month old daughter. Magic times indeed. Enjoy. & twins aren't that bad, they've been sleeping through the night since they were 8 weeks old.)
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I'm a bit hesitant to say it, but I'll say it anyway...
Does it pass an overnight test of Heaven on maximum settings?

You might read through this thread (pasted below), for my advice on ensuring the stability of a Kepler GPU, including downclocking in 13 Mhz intervals until an overnight run of Heaven doesn't crash and doesn't produce TDR dmp files in C:\Windows\LiveKernelReports\WATCHDOG

http://www.gpugrid.net/forum_thread.php?id=3852

-- Jacob