had same issue for anyone with this problem when pc boots press f2 the fans are being controlled by motherboard,with mine I disabled fan control saved setting and all fans are working ,so the problem is fixed in bios settings,easy

Took me 7 years of nightmares in Linux before finding this. Thank the awesome person that told me.
 
On my 970 FTW+ ACX 2.0 there's a hidden dip switch on the top of the card labeled (Master / Slave). Evga killed the manual for this gpu, so don't have a pic or proper instructions of what the dip switch is supposed todo. Here's roughly what it looks like:

 
If it helps, pls reply to let others know. thx.

got it. linked to another forum post that explains what the switch does. who knows why it's set to master by default.
also, be smart. shut off the pc when changing that dip switch. hf.