Hello all forum members,
 
The onboard  'slave - master' switch is a wonderful feature, another + on the redesigned 970 GTXs, but I am still trying to find out
the proper switch position for SLI configurations running under the Precision X   Auto Fan Control.
 
A technical input would be very much appreciated. 
 

I run both of my ftw+'s on the slave firmware. They run at 58C/56C respectively with a custom fan curve.

Either one is fine. One is for a more aggressive fan profile.

Thanks, NO_sauce,
But please be  more precise, witch profile is more aggressive than the other?
And if all fans are governed by Precision X   by custom set temperature curve, you
by pass the automatic spin up that is scheduled at above 60 degrees C.
Would that be correct having, the no1 card master, and the rest of them slave to the master card?

Doesn't matter. Master is the default bios for the card and the slave has a higher power target and more aggressive fan profile for overclocking. Yes, having a custom fan curve negates the higher preset on the slave bios. If you are not overclocking just keep them on master.

"Master" is default factory BIOS #1.
"Slave" is slightly adjusted BIOS #2.

Don't let the terms "master" and "slave" make you think of the old IDE days. It's nothing like that. Master has no control over slave. The cards don't talk to eachother about their BIOS switch positions. It doesn't have anything to do with SLI functionality particularly. It is just BIOS choice 1 or BIOS choice 2.

You can operate the cards as master, master. Or, slave, master. Or master, slave. Or, slave, slave. Whichever choice you make, the switch position for each card only affects the behavior of that one card.

Dear Slayer27 and Ty Ger07 ,
I really thank you much for your technical inputs, I will stick to Master Position,
since I am not planning of overclocking shortly, my brand new cards work fantastic, except a sitting
issue on the 5th PCI ex Slot on my Z87 Classi due to the absence of the latch of that slot.
  

No problem. I hope you enjoy your 970s, I loved mine and they clocked really well.