hapkiman
Something is wrong with your fans then.  The fans in my FTW 1080 are extremely quiet at 30%.  

FTW fans are bigger and thus quieter. In addition my 1080 FTW fans max at 2700rpm while the smaller 970 SC fans ramp all the way up to 4000rpm if I crank them up to 100%.

birthdaymonkey

bcavnaugh
That is a
 

Yeah, it's quite an impressive design. Portable and only slightly bigger than a console, yet you can get a full fat GPU in it. And it somehow keeps everything cool without any intake or exhaust fans.
 

This is my setup. I run without the filter because it impedes airflow too much. With the system on my desk it doesn't get any cat hair in it even without the filter. The card looks nice as well. Unfortunately, as you can see, it's pretty much positioned to beam GPU sound directly at my head.

Hello - I think the issue is seen here, you are way too close to the GPU - while sitting that close you will hear the fans even at 30%, not to mention that you have a vent next to the fans which usually increase the fan noise. I have very sensitive hearing (so much that amplifier / speaker hums drive me Crazy!) and I can hear my Asus Strix 1080 at 30% from 15 -18 inches away with my case open. With my case closed and 1m away from me, I dont hear anything. I am pretty sure that your video card orientation, and case vent design is causing this issue. Try moving the case maybe 1m away and see if the noise level improves - Also Download Afterburner to setup a custom fan curve that will fit your noise / performance needs. I dont think it is a fan issue, if it was it would be much louder LOL - case in point my evga GTX 970 which had fauly fan bearings....yeah.......that noise.......brings back.....memories.............like an old train trying to speed up.............and the noise it makes............LOL 
 
GL

that is one tiny case...  
when you look at your GPU temps, what is happening there?  
 
i had a Gigabyte G1 1080 that made this sound every time the fans turned on: https://www.youtube.com/watch?v=JudXFqkoEmw
the card kept heating up while idle, so eventually it would hit the threshold (no matter if i set it to 45, 50 or 55°C) where the Fans turned on, but a "mild breeze" was enough to cool the heatsink down by 1°C ...then it turned off again for like 5 or 10 seconds until the GPU temp went that 1°C up again... and it did that on/off loop forever.  
Solution one: custom fan curve, put it to 30% and you can't hear it...  
Solution two: better airflow in your case so it doesn't heat up like that.  
the Gigabyte card also had horrible Coil Whine, that Fan Stop LED was not indicating what the Fans were actually doing and i had an overall bad impression of the Gigabyte card this time so i send it back to the Shop and got an EVGA 1080 FTW instead. (which made an awesome impression, but now i have to deal with the VRM temperatures nonsense... *sigh*)  
in the meantime i added 3 more case fans which brings me to a total of 6x 140mm Case Fans (all super silent at 5v), 1x 120mm CPU Fan (1000rpm when gaming, 500 when idle), the 120mm Fan in the PSU also has a Zero Fan Mode, just like the GPU. I seriously can't hear the PC anymore when idle... and even when gaming it is very negligible. (the noise the heater in my room makes drives me nuts, but that is a different topic)  
pics -> http://imgur.com/a/6ERQm
full excessive build log -> http://imgur.com/a/FBDEo
i also made the jump and threw out all my internal HDDs and the System is as silent as it possibly can be without Watercooling,  
i've even put a noise dampening kit in there (not sure if that actually did anything, but it looks damn good and plugged a lot of ugly holes in the case).  
 
anyway with your ...mini ITX? case i'm afraid you won't have many options to add case fans.  
 
my GPU is now, after hours of being idle, at 33°C and 0 RPM (with the original bios which i intend to NOT update (i guess when you get your RMA back it will have the new BIOS with the aggressive fan curve already installed, so that will get louder), my thermal pad mod is awaiting shipping, that should be enough anyway.).  
 
//edit: i almost didn't notice that (signed?) Captain Kirk picture on your desk :D  

I found a semi-solution to the problem.
 
I created a batch file to reinitialize the GPU driver. If I wait until the GPU has cooled down and then run my batch file, the fans on the GPU act as though the system had just been rebooted. They stop twitching, and I've once again got a "0 dB" graphics card. You can do this using MS's Devcon command line utility or the third party Devmanview utility. Interestingly, it doesn't work unless I allow the system to sit for a while. But if I reinit the display driver after an hour or two of idling, the fans stop twitching!
 
This does make me wonder why EVGA can't just make the card behave properly by default without requiring this hackish workaround.
 

It really sounds like in your case, after stressing it, the card's temperature is just too close to the turn on/iff point and can't cool itself enough while idling with no fan (since it's already a bit hotter than fresh from boot). Probably because your card doesn't get any airflow while in passive mode as the case doesn't promote much airflow on its own. Are you using Precision XOC (or something like MSI Afterburner) to control the fan curve manually?
 
One way to help with the behaviour is by tweaking the fan's hysteresis setting in Precision XOC or MSI Afterburner. That way, you can, for example, set the fans to start spinning after it reaches 45C, but only stops spinning (on cooldown) when it reaches a temperature lower than the 45C (roughly the amount of hysteresis you set, e.g. at hysteresis of 5C, it would spin until it reaches 40C). That can help a lot with getting away from the "twitchy" fan region and to sufficiently low temperatures where the card can passively cool itself while idling.
 

birthdaymonkey
The fact that my 1070's fans remain motionless after a reboot suggests that it's at least possible in theory for it to stay still too. But as soon as the fans are spun up (either due to a gaming load or if I turn the fans on in PrecisionX), when the card returns to idle, the fans twitch.

For my 980ti the fan twitch comes from the GPU bouncing off the 60C fan spin up temp. I suspect it is not a bug post fan spin up as you suggest. Check the temp when you get the twitching and see if they go hand in hand. At least for me the twitch sound has disappeared or I no longer hear it after a few months.

It's really not the temperature of the card. It idles in the high 30s/low 40s.
 
The fans twitch regardless of the temperature. Have a look at your own cards and you'll see it. Most people don't notice because their card is facing the bottom of the case, but there's something in the fan control software that keeps sending it a bit of voltage when it idles. I can spin the fans at 30% until the temp goes down to <30 and the fans will still twitch as soon as the card returns to idle.
 
Rebooting (or, as I just found, reinitializing the display driver) fixes the issue. The fan doesn't spin up again (or move at all) until it gets up to the high 50s when I start playing a game.

Well then it sounds like it is indeed a bug (though could be driver bug not EVGA firmware). My 980ti SC for sure doesn't twitch when the temps are cool enough so it's either an issue with ACX 3 (980ti has ACX 2) or the 1070 SC firmware, or something with your driver/software setup.
 
So at this point I'd say you want either someone else with a 1070 SC to confirm the same behavior, or if you have a spare drive do a fresh install of Windows to see if the problem persists.

ZeroBANG
that is one tiny case...  
when you look at your GPU temps, what is happening there?  
 
i had a Gigabyte G1 1080 that made this sound every time the fans turned on:
the card kept heating up while idle, so eventually it would hit the threshold (no matter if i set it to 45, 50 or 55°C) where the Fans turned on, but a "mild breeze" was enough to cool the heatsink down by 1°C ...then it turned off again for like 5 or 10 seconds until the GPU temp went that 1°C up again... and it did that on/off loop forever.  
Solution one: custom fan curve, put it to 30% and you can't hear it...  
Solution two: better airflow in your case so it doesn't heat up like that.  
the Gigabyte card also had horrible Coil Whine, that Fan Stop LED was not indicating what the Fans were actually doing and i had an overall bad impression of the Gigabyte card this time so i send it back to the Shop and got an EVGA 1080 FTW instead. (which made an awesome impression, but now i have to deal with the VRM temperatures nonsense... *sigh*)  
in the meantime i added 3 more case fans which brings me to a total of 6x 140mm Case Fans (all super silent at 5v), 1x 120mm CPU Fan (1000rpm when gaming, 500 when idle), the 120mm Fan in the PSU also has a Zero Fan Mode, just like the GPU. I seriously can't hear the PC anymore when idle... and even when gaming it is very negligible. (the noise the heater in my room makes drives me nuts, but that is a different topic)  
pics ->
full excessive build log ->
i also made the jump and threw out all my internal HDDs and the System is as silent as it possibly can be without Watercooling,  
i've even put a noise dampening kit in there (not sure if that actually did anything, but it looks damn good and plugged a lot of ugly holes in the case).  
 
anyway with your ...mini ITX? case i'm afraid you won't have many options to add case fans.  
 
my GPU is now, after hours of being idle, at 33°C and 0 RPM (with the original bios which i intend to NOT update (i guess when you get your RMA back it will have the new BIOS with the aggressive fan curve already installed, so that will get louder), my thermal pad mod is awaiting shipping, that should be enough anyway.).  
 
//edit: i almost didn't notice that (signed?) Captain Kirk picture on your desk :D  

Haha, yeah that's my "signed" Captain Kirk photo. I think it's actually a fake signed Captain Kirk photo - my friend got it for me at a flea market. 
 
Glad to hear from a kindred silent PC enthusiast. Your machine sounds a lot like my old Fractal XL-R2, in which I had installed 3x140mm Noctua NF-P14 and ran them most of the time at 5v, with two Noctua PWM fans on the CPU heatsink that ran at about 400-500 RPM at idle. The problem with PC silencing is that there's always another sound. Once you get rid of the fan noise, you start to hear electrical noise - (e.g. coil whine). And even those 5v 140mm fans make a noise - if your room/system are quiet enough you'll hear it. 
 
With my current build, I've got one Scythe slim 120mm fan idling at ~500 RPM, and I can't hear it (for now). My Corsair SF-450 PSU also turns its fan off at idle. With no spinning disks or case fans, and no components that make coil whine (for now), I have a pretty silent system, which is why the twitching GPU fans were annoying me so much. The next step is to get a better (14cm) fan on the Big Shuriken II heatsink, but to do that I have to clip some metal, which seems like a hassle... although I already bought the fan, lol.
 
With this workaround (reinitializing the display driver when I want the computer to be quiet after a gaming session), I have to decide whether I want to go through with the RMA for the VRM thermal pads... I think I might keep it and mod myself since I have the Samsung memory and the pool of refurb cards will be biased in favor of the ones people wanted to get rid of.

birthdaymonkey

bcavnaugh
That is a
 

Yeah, it's quite an impressive design. Portable and only slightly bigger than a console, yet you can get a full fat GPU in it. And it somehow keeps everything cool without any intake or exhaust fans.
 

This is my setup. I run without the filter because it impedes airflow too much. With the system on my desk it doesn't get any cat hair in it even without the filter. The card looks nice as well. Unfortunately, as you can see, it's pretty much positioned to beam GPU sound directly at my head.

 
Have you turned the case around and placed it in the Left Side or even behind your Monitor?
This would put you Vent on your Computer on the other side not facing you.