After I had a similar problem with one of my GTX750ti some 4 weeks ago, today my GTX970, during crunching a PABLO_adaptive_goal_KIX, was switching back to default clock 1152MHz.
Only after rebooting the PC, the clock value could be increased via the NVIDIA Inspector. However, after a few minutes, the GPU clock again falls to 1152MHz.
At this clock, TDP usage is about 55% (whereas it was about 80-90% [depending on the specific task] when running at around 1380MHz).
And again, the clock value 1152MHz cannot be changed manually, in neither direction, except when rebooting the system.
BTW, NVIDIA Inspector and GPU-Z show exactly same values.

Both the GTX750ti and the GTX970 have been crunching four about 1 year.
Do I have to assume that after a crunching period of about 1 year, the cards become defective? BTW, I always took good care of the temperature situation, both GPUs never got warmer than 60-63°C.

Has anyone else made the same kind of experience?

Yes, it is very intermittent and random, and has occured on multiple of my GPUs, only maxwell. Both of my 970s have dropped to 1164mhz multiple times and sometimes they stay there until the computer is rebooted. I believe it has nothing to do with the GPU itself, as it is probably a software issue that one of the scientists can investigate.

Can this be the (same) reason why the older 980ti surpasses the 1080 which should be noticably faster just from its specification?

See also this posting:
http://www.gpugrid.net/forum_thread.php?id=4494&nowrap=true#46410
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I would love to see HCF1 protein folding and interaction simulations to help my little boy... someday.

Can this be the (same) reason why the older 980ti surpasses the 1080 which should be noticably faster just from its specification?

Yes, it is very intermittent and random, and has occured on multiple of my GPUs, only maxwell. Both of my 970s have dropped to 1164mhz multiple times and sometimes they stay there until the computer is rebooted. I believe it has nothing to do with the GPU itself, as it is probably a software issue that one of the scientists can investigate.

When you say that the reduced GPU clock "sometimes" stays until the computer is rebooted - does this mean that sometimes you are able to raise the clock again without rebooting? In my case (with the GTX750ti as well as with the GTX970) there is no way to change the clock - neither up nor down - until the PC is rebooted.

Further, after the reboot of the system, can you go back to the same high clock as before without the clock reverting back to the default value for lenghty time?
In my cases, the clock would revert back within few minutes.

Final question: for how many months have your cards been crunching? I am asking this because, as said before, with both of my cards this behavour started about a year. And it's never ever happened before. And this seems strange.

... I truly think this is some type of software bug inside the application itself.

When this morning I took the first look at my PCs, I noticed the following situation on both the one with the GTX970 and also the one with the GTX750ti (both crunching a PABLO_adaptive_goal_KIX):

In the NVIDIA Inspector, the GPU clock was down at 540 MHz(!), Memory clock 2700MHz (default), GPU Load 0, Power between 84 and 89%. Changing the clock values by the sliders not possible.

In GPU-Z, no values were shown at all for GPU clock, memory clock, GPU load, Video Engine load (which normally is 0 anyway) - no values means a "-" in the fields were normally values (or "0") are shown. Power consumption shows same values as the Inspector.

However, the "progress" column of the BOINC manager shows a progress in the percentage; as it seems to me (but I might be mistaken) with about same speed as usual.

What's going on with these two cards?

Is the problem still occurring? It keeps happening, but only to my 970s. They are doing a mix between folding@home and GPUGrid, and they seem to randomly go to stock clock. When I restart the computer they almost always jump right back up to boost clock but then sometime later they drop down again. Both cards are on different drivers so it could be a persistent error with the driver. Sometimes when I start folding on top of GPUGrid it raises the boost clock, but sometimes it stays at stock clock. I am truly baffled.

Try to turn off graphic acceleration in your browser, and in Microsoft Excel too (if you have it).

Try to turn off graphic acceleration in your browser, and in Microsoft Excel too (if you have it).

Try to turn off graphic acceleration in your browser, and in Microsoft Excel too (if you have it).

I could not find such a setting in the MS Edge browser (the only one on this system)

Whenever crunching PABLO_adaptive_goal WUs, the card is showing the same behaviour: GPU clock falling back (not immediately, but after a while) to default 1152MHz whenever it's overclocked beyond around 1250MHz :-(

yes, this is the PC I do most of the Internet browsing :-)

So I now changed the settings according to your instructions and restartet the machine.
Let's wait and see whether this helps. I will report here.

Let's wait and see whether this helps. I will report here.

Have you tried to update the firmware (BIOS) of the card?

Have you tried to update the firmware (BIOS) of the card?

I've seen my GTX 980 Ti GPUs sometimes crunch at non-boost 3d clocks (like 1150), when they normally crunch at boost 3d clocks (like 1320).

When they are in this "broken mode", while I'm crunching, if I run GPU-Z, then click the question mark "?" to do the "PCI Express Render Test", it shows a graphic, and the GPU clock ramps back up to boost 3d clocks. Then when I close the GPU-Z windows, it goes back down to non-boost 3d clocks, even though I'm still crunching GPUGrid tasks.

Long story short: I believe the driver is not correctly recognizing that a 3d compute app wants full boost 3d clocks. I'm not sure if there's a setting the app can make to do that, but I suspect it's a driver bug.

And it won't get fixed, unless you can supply a completely reproducible case, and then can report it and get them to listen. I've tried to get that reproducible example, but have never been able to get it. If you have one, please list the steps (all of them, details matter!) here.

Thanks,
Jacob

When they are in this "broken mode", while I'm crunching, if I run GPU-Z, then click the question mark "?" to do the "PCI Express Render Test", it shows a graphic, and the GPU clock ramps back up to boost 3d clocks. Then when I close the GPU-Z windows, it goes back down to non-boost 3d clocks, even though I'm still crunching GPUGrid tasks.

Long story short: I believe the driver is not correctly recognizing that a 3d compute app wants full boost 3d clocks. I'm not sure if there's a setting the app can make to do that, but I suspect it's a driver bug.

I've seen my GTX 980 Ti GPUs sometimes crunch at non-boost 3d clocks (like 1150), when they normally crunch at boost 3d clocks (like 1320).

When they are in this "broken mode", while I'm crunching, if I run GPU-Z, then click the question mark "?" to do the "PCI Express Render Test", it shows a graphic, and the GPU clock ramps back up to boost 3d clocks. Then when I close the GPU-Z windows, it goes back down to non-boost 3d clocks, even though I'm still crunching GPUGrid tasks.

Long story short: I believe the driver is not correctly recognizing that a 3d compute app wants full boost 3d clocks. I'm not sure if there's a setting the app can make to do that, but I suspect it's a driver bug.

For what it's worth, I am experiencing exactly the same issue with my 970 on win 10. Sometimes the clock comes down because I start Chrome (which I can understand) but sometimes it just drops the clock for no reason. GPU usage is still pegged at 100% however.

I really have no clue.

By now I am pretty much convinced that the problem has to do with:

1) Win10 itself, or
2) the WDDM overhead, or
3) the driver, or
4) a mix of above

In my mind, the possibilities are:

a) It's actually working correctly, in a situation where the code is moderately to heavily cpu-bound and there is no tangible benefit toward running at a faster gpu clock

or

b) Stupid NVIDIA driver is stupid.

....

It is very likely to be b.

Unfortunately, after the change from CUDA 65 to 80 a few days ago, and the compulsary driver update from 376.53 to 381.65, the problem has become even worse.
It looks like as if crunching above the default clock 1152MHz in no longer possible.

For example, I had recent tasks run at 1280MHz and around 77% TDP. After a few minutes, the clock fell back to 1152MHz, TDP around 55%.

Until a few months ago, it was no problem at all with this card to crunch at 1420MHz and about 95% TDP.

What's going wrong?

Still today, I will have to update driver on the PC with the GTX750ti inside, with which I have been experiencing the same problem for a while.
So I am afraid that also there, the problem will become even worse.

It would really be interesting how many other crunchers now have the same problem with a GTX970 in combination with the new software acemd_918.80 and the new driver 381.65.
Here, even mild overclocking makes the GPU jump back to default clock 1152MHz :-(((

Have you tried using a different tool to do your overclocking? I overclock with MSI Afterburner, and highly recommend it.

It would really be interesting how many other crunchers now have the same problem with a GTX970 in combination with the new software acemd_918.80 and the new driver 381.65.
Here, even mild overclocking makes the GPU jump back to default clock 1152MHz :-(((