GPU core throttles mysteriously

Alright, now this one's got me. Every so often (every day or two, but not predictably as far as I can tell), my EVGA 460 1gb's core clock goes from 840 to 405 mhz. It then sits there, and I can't budge it. I use EVGA Precision to manage my GPU OCing, but neither it nor Afterburner can change the clock once it's decided to sit at 405. Only rebooting fixes the problem, as far as I can tell. This has also happened in games (Crysis 2) before; I suddenly drop from 60 fps to around 27. I'm almost sure that this is the same problem, though I hadn't yet noticed the change in the clock when those fps drops happened, only the drop in performance.

I don't think this is a reporting error in Precision/Afterburner, because Folding@Home reads 426 ns/day instead of 857, if I remember the second number correctly. That's roughly proportional to the drop in the clock rate.

I got a screenshot right when I noticed the drop in clock rate. As you can see, the rate then dropped to 51 mhz, but that went back up to 405 under load.
http://tinypic.com/r/307yesg/7

I haven't yet found a trigger for this. Sometimes Folding just starts in at half speed, and I'm not sure if it's just started because I haven't looked at the core clock before turning it on. I use this as an example because I do more Folding than I do gaming, so I have more experience with the problem in that context.
 
Solution
405 is the 2d clock speed, 51 mhz is the idle speed. It's normal for the card to throttle down like that but it shouldn't get stuck there. I agree with those suggesting a drive update.

benski

Distinguished
Jun 24, 2010
1,611
0
19,960
405 is the 2d clock speed, 51 mhz is the idle speed. It's normal for the card to throttle down like that but it shouldn't get stuck there. I agree with those suggesting a drive update.
 
Solution
Nope, I'm current. 280.26.
Folding seems to be the problem. I may have falsely accused Crysis 2 by quitting Folding shortly before opening it (that's my hypothesis). It's still not predictable, though. I ran FAH all day today: it started out at 840 happy mhz, but when I got home it was idling at 51. "Core not running." The clock didn't stick; it works fine in other applications, and FAH boots again with 850 mhz (OCed up again).
I don't get above 60C in folding, but the EVGA stress test gets 68C...still fine, though.