My card can do the same after gaming when its hitting 60c but stops when temperature goes down. Have you checked the temps when its doing it? 

Thanks Shaman, appears to be the same. No chance I'll RMA and spend another 2 weeks without a PC ha ha - besides, everyone's RMA replacement seems to be having the same issue so RMA would be pointless. I hope EVGA is right and it's a driver issue. Meanwhile I might try a custom fan profile:
 
40C=50% 50C=65% 60C=75% 65C=85% 70C=100% (curtesy of Sean1976)
 
 
Edit 1: custom profile made no difference: it sounds like the fans are revving up and down all the time, however no fan speed indicator indicates this. Sounds like a howling wind in a room, if that makes sense?
 
Edit 2: turning off Precision removes the revving issue completely (good!), the 'howling like the wind', hoever persists, albeit quieter.

F34R
Edit 2: turning off Precision removes the revving issue completely (good!), the 'howling like the wind', hoever persists, albeit quieter.

F34R

Sajin

F34R
Edit 2: turning off Precision removes the revving issue completely (good!), the 'howling like the wind', however persists, albeit quieter.

See bold... :/

Fans do make a little bit of noise.
 

F34R

Sajin

F34R

Sajin

F34R
Edit 2: turning off Precision removes the revving issue completely (good!), the 'howling like the wind', however persists, albeit quieter.

See bold... :/

Fans do make a little bit of noise.
 

Ha ha ha it's not my first GPU so I know, but I've never heard one sounding like howling wind so that's not right, right?

My rig always makes a howling wind noise with its blower style cards and delta case fans. 
 
Could you post a video?

F34R
Ha ha!
 
I'll try and make one later this week, prob Thu, haven't got time before that. Tried the new driver, but the sudden revving continues even with Precision disabled. The howling is often and at intervals, not continuously. Hoping it's maybe a card BIOS thing?

I suggested it could be a VBIOS problem, but they told me it was a defective card. It seems there are lots of defective cards with this problem though, this is the video I recorded:
 
https:// www.youtube.com/watch?v=I9KSrL8duII
 
Mine sounded like wind howling too.

There seem to be many, in that case, with the new ACX 3.0 cooler. People's replacement cards having the same issue and all - so I'm not going to (endlessly) RMA anything right this instant (mine is a step-up, traded in a perfectly good Ti for this one and spent over a week without a PC so not eager to go through that again). Temps are fantastic, and Precision overlay doesn't show any revving even when it's audible, strangely.

So, my 1080 SC had the same issue, where the fans would randomly run at double speed for a few seconds. But it only happened once every few hours so I was fine with it.
 
I get these thermal pads from EVGA which are supposed to help with vrm thermals. I install them and the card appears to run cooler, but I notice something when testing it. The fan revving now occurs randomly every few seconds under any kind of load.
 
As for troubleshooting, I re-seated the card multiple times with no improvement. Manually setting the fans to 50% (using any software, speedfan, precision, inspector etc.) yields a constant speed of 1830rpm. Under full load it drops to 1300-1500 (varying wildly) and periodically spiking. This looks a lot like interference in the PWM signal coming from the controller. (can anyone with an ACX 3.0 and an oscilloscope confirm?)
 
Below are the fan speed and frequency/power graphs of the card under load. Every vertical delimiter is 1 second.
You can see the instant I put load on the card.
 
Since it doesn't look like RMA will fix the issue, and I can't afford the hybrid upgrade kit, I feel like I'm out of options. Any ideas?