I'f i change my GTX 1080TI FE fan curve speed will this kill my card ? i have managed to get my card down too 75 degrees steady on pubg running at 64% fan speed on msi afterburner will this be okay?
It will if it's set too low to actually cool the card or if you disable software automatic fan control by mistake. Depending on the card manufacturer or PC Specialist you could be voiding the warranty if you're touching voltages.
That change to the fan curve sounds fine - 64% fan speed isn't all that aggressive afaik for a blower cooler, and 75 degrees is a very fair temp for a GTX 1080 ti
Doesn't look like it covers anything above 74 degrees. You should probably space out the nodes a bit more so that the top one kicks into 100% if the card gets to an unreasonable temperature.
But i have been running MSI afterburner in game to check my temps and having that fan curve set up it never goes over 75 degrees. Cause i think out the box the gtx1080ti fan curve speed is a lot lower for it to be quiet.
I'd still note TheGeeza's comments that you could have another step or steps higher up so that if the GPU ever did go beyond that temp (e.g. if you forget to dust it for a bit, or ambient temps get very high etc..) it would get some extra cooling.
But ~65% fan speed for a blower cooler, as far as I know, is perfectly acceptable.