You can download Precision X and enable KBoost while playing games which will lock your GPU in its boost clock. (Doesn't let it downclock/throttle).

Maybe it's hitting power limit?

bcavnaugh
 
If you are thinking about putting your Card Under Water did you but a Card what will support a Water Block or support the Hybrid from EVGA?

pretty sure all 980tis on the market right now are reference PCB so any TitanX-compatible waterblock (incl. hybrid) will fit.

anzial
Maybe it's hitting power limit?

Perhaps.  However, I've tried it under the entire range of overvoltage available.  There is no apparent difference between 0 mV, 49 mV, and full additional power.  If it's hitting the power limit, then I would expect the OC Tool to show instability.  However, none of the games (Dragon Age Inquisition, Metro 2033, Rome II Total War, Elite:  Dangerous, Star Citizen) or benchmarks (3DMark, OC Scanner) are unstable.  It's rather baffling.
 
The odd thing about this card is that it seems to be a "golden nugget" in terms of its ability to overclock the GPU in some tests and games.  It's just got this odd little bug/weirdness with downclocking to a level that's not specified regardless of the temperature or power.  (I have been running the tests at 100% fan speed regardless of load.  The computer sounds like a jet spooling for takeoff.  Heh.)
 
As for water cooling, I'd planned to stick an EK Titan block on it.  (Though I may wait for the newly announced 980 Ti blocks from EK just to see what the differences are.)  I have a 5960X on a custom water loop and there is more than enough radiator space to handle the 980 Ti.  The downclocking issue is unexpected and isn't giving me a great baseline for what to do under water.

shan2
 
 However, I've tried it under the entire range of overvoltage available. 

You do understand that voltage and power are different things, right? If the cards are hitting TDP (power limit in watts, not volts), they will downlock, there will be no instability.

mokkema

bcavnaugh

shan2
Thanks for the suggestion.  I just tried it and the GPU clock started off at 1500 MHz, but got bumped down to 1283 MHz during the 3DMark run.  The GPU temperature never exceeded 55 deg C because the fan profile is super aggressive.
 
Maybe if I put it under water, it would do better?  I've no idea why this is occurring.  I upgraded for the GTX 680 SC and overclocking that GPU was far more straightforward by comparison.

If you are thinking about putting your Card Under Water did you buy a Card what will support a Water Block or support the Hybrid from EVGA?

What 980Ti wouldn't support watercooling right now?

 

anzial

bcavnaugh
 
If you are thinking about putting your Card Under Water did you but a Card what will support a Water Block or support the Hybrid from EVGA?

pretty sure all 980tis on the market right now are reference PCB so any TitanX-compatible waterblock (incl. hybrid) will fit.

See http://www.coolingconfigurator.com/
EVGA GeForce GTX 980 Ti 06G-P4-4990-KR and EVGA GeForce GTX 980 Ti Superclocked 06G-P4-4992-KR are supported.
Their are what 5 EVGA GTX 980Ti Cards not including the HC & Hybrid Models.
EK only shows 2 out of the 5 Cards, this would then mean that 3 of the 5 cards are NOT Supported for a Full Water Block.
 
Cards Not Yet Supported for a Full Water Block:
06G-P4-4991-KR EVGA GeForce GTX 980 Ti ACX 2.0+
06G-P4-4993-KR EVGA GeForce GTX 980 Ti Superclocked ACX 2.0+
06G-P4-4995-KR EVGA GeForce GTX 980 Ti Superclocked+ ACX 2.0+
 
So that would be less than half are supported. *Right Now

There's another little quirk I noticed.  The white and red arrows showing the base clock and boost clock don't change with the GPU Clock Offset on Precision.  Is this normal?
 

bcavnaugh
See http://www.coolingconfigurator.com/
EVGA GeForce GTX 980 Ti 06G-P4-4990-KR and EVGA GeForce GTX 980 Ti Superclocked 06G-P4-4992-KR are supported.
Their are what 5 EVGA GTX 980Ti Cards not including the HC & Hybrid Models.
EK only shows 2 out of the 5 Cards, this would then mean that 3 of the 5 cards are NOT Supported for a Full Water Block.
 
Cards Not Yet Supported for a Full Water Block:
06G-P4-4991-KR EVGA GeForce GTX 980 Ti ACX 2.0+
06G-P4-4993-KR EVGA GeForce GTX 980 Ti Superclocked ACX 2.0+
06G-P4-4995-KR EVGA GeForce GTX 980 Ti Superclocked+ ACX 2.0+
 
So that would be less than half are supported. *Right Now

You are extrapolating in absence of confirmation. EK website is not an industry standard, so they can't be considered to a yardstick to measure compatibility or incompatibility of waterblocks. They only guarantee certain compatibility for their own products but they do not take any kind of responsibility to provide absolute and universal information about compatibility of hardware and related watercooling equipment across the entire world. In this case, they can only ascertain that two EVGA models of 980ti are compatible with their blocks but they do NOT explicitly exclude other reference-PCB EVGA 980ti. I bet $100 to $1 that they just looked at the pictures and picked those evga cards that have reference coolers without actually seeing or checking compatibility of each of evga card against their blocks. They just being careful but ask EVGA, does the PCB of those other 3 980tis you list differ in any way from the first 2 that EK listed as compatible? Again, I'm sure there's no difference, with one caveat - EVGA or even nVidia may change reference design later (in a month or more) and it may render videocards incompatible. But if you bought any 980ti in the past week and the next couple of weeks, they will ALL have the same exact PCB and accordingly, ALL of them will be compatible with current crop of TitanX waterblocks.
 
Don't believe me? Just ask EVGA or you can actually send a request to EK to check the other three models. I'm sure they'll show up there in matter of days.

anzial

bcavnaugh
See http://www.coolingconfigurator.com/
EVGA GeForce GTX 980 Ti 06G-P4-4990-KR and EVGA GeForce GTX 980 Ti Superclocked 06G-P4-4992-KR are supported.
Their are what 5 EVGA GTX 980Ti Cards not including the HC & Hybrid Models.
EK only shows 2 out of the 5 Cards, this would then mean that 3 of the 5 cards are NOT Supported for a Full Water Block.
 
Cards Not Yet Supported for a Full Water Block:
06G-P4-4991-KR EVGA GeForce GTX 980 Ti ACX 2.0+
06G-P4-4993-KR EVGA GeForce GTX 980 Ti Superclocked ACX 2.0+
06G-P4-4995-KR EVGA GeForce GTX 980 Ti Superclocked+ ACX 2.0+
 
So that would be less than half are supported. *Right Now

You are extrapolating in absence of confirmation. EK website is not an industry standard, so they can't be considered to a yardstick to measure compatibility or incompatibility of waterblocks. They only guarantee certain compatibility for their own products but they do not take any kind of responsibility to provide absolute and universal information about compatibility of hardware and related watercooling equipment across the entire world. In this case, they can only ascertain that two EVGA models of 980ti are compatible with their blocks but they do NOT explicitly exclude other reference-PCB EVGA 980ti. I bet $100 to $1 that they just looked at the pictures and picked those evga cards that have reference coolers without actually seeing or checking compatibility of each of evga card against their blocks. They just being careful but ask EVGA, does the PCB of those other 3 980tis you list differ in any way from the first 2 that EK listed as compatible? Again, I'm sure there's no difference, with one caveat - EVGA or even nVidia may change reference design later (in a month or more) and it may render videocards incompatible. But if you bought any 980ti in the past week and the next couple of weeks, they will ALL have the same exact PCB and accordingly, ALL of them will be compatible with current crop of TitanX waterblocks.
 
Don't believe me? Just ask EVGA or you can actually send a request to EK to check the other three models. I'm sure they'll show up there in matter of days.

Fine, you are the expert here on the Forums. Lets keep the Subject on Track.
 
Sorry OP for going off Subject.

freEVfoldinGA
This sounds like run of the mill unstable overclock to me. I haven't made my 980ti crash it's clocks down through an unstable OC yet but your 1280Mhz mention makes it sound like it's returning to stock, does the memory also "downclock" back to the stock 7Ghz when this happens? Does it then take a restart to restore the clocks to their OC speeds? Not all instability presents itself with bright easy to see artifacts, a black screen, or a driver crash message, and at the high speeds you're attempting odds are higher that it's unstable rather than stable.
 
If you really want to continue to assume it's stable then turn on all the limit graphs in MSI AB or EVGA Afterburner and see what if any you're hitting. If you're not hitting any any limits and it's downclocking by more than one or two steppings (so 13Mhz or 25Mhz) then it must be instability.

That makes sense.  I'll have to try the overclock in smaller increments and try to see when all of the benchmarks run at the set GPU speed.  (My old 680 would crash fairly obviously when I overstressed it.  It didn't even occur to me that the 980Ti could be recovering after a mini-crash.)  Thanks!

Edit your cards vBIOS to disable boost. Latest version of nvflash and maxwell bios tweaker can be downloaded here. Use GPU-Z to save your cards vBIOS to your desktop for editing. 

shan2
but it's easier to see what's happening with the water loop that way.

It's also better for algae when there's light in the waterloop ;) Sometime ago I've read some suggestions on xtremesystems that it's better to have a very dark (black tubing, no light sources etc) waterloop which will reduce probability of algae survival. To each their own, but you can actually run a pure distilled water with no additives (including no biocides) and have no problems with algae because it doesn't thrive in the dark :D Just some food for thought.