Sajin
Clocks are most likely still too high. Try this 1420 one.... https://www.mediafire.com/?wy19k882j28de0l
 
Idle voltages have been adjusted too. 

Testing now

Glad to hear the new vbios corrected the problem. Which one finally fixed it? The one I completely redid? 
 
1430mhz...1420mhz..1408mhz...1420mhz... That is happening most likely because of how high your gpu temp is. Running the gpu fans higher should fix that.

Sajin
Glad to hear the new vbios corrected the problem. Which one finally fixed it? The one I completely redid? 
 
1430mhz...1420mhz..1408mhz...1420mhz... That is happening most likely because of how high your gpu temp is. Running the gpu fans higher should fix that.

First post says it all In big bold words, check it out

phaseshift
How long does the process take for 
 
"#3 Type nvflash --save Default_980Ti.rom"
 
Mine just says "NVIDIA Firmware Update Utility (Version 5.218) Modified Version by Joe Dirt

Make sure your using the correct nvflash for your system (windows 7/8/10 and 64/32 bit)
 
Mine did that too once.. I think it was because I was using a windows 7 version on windows 10 ..

Guys, I'd like to edit the bios of my 980 Ti Hybrid, to achieve the followigìng:
Max safe voltage (I assume first slider to 1.281)
Max power limit and/or TDP (I assume 75W+75W+150W, even if my bios seems higher for 6 pins)
Keep stock boost, and stock at default values of PrecisionX, but maxed when moving the sliders...
Could someone suggest me? Thanks!

gpvecchi
Guys, I'd like to edit the bios of my 980 Ti Hybrid, to achieve the followigìng:
Max safe voltage (I assume first slider to 1.281)
Max power limit and/or TDP (I assume 75W+75W+150W, even if my bios seems higher for 6 pins)
Keep stock boost, and stock at default values of PrecisionX, but maxed when moving the sliders...
Could someone suggest me? Thanks!

 
Not sure what you are asking for, could you re state the question in a different way 
 
btw
you can just download the one that Sajin made on the first post where I have it in bold text  It will work fine with your card even if it is a water cooled 980 ti if I remember correctly.
(someone confirm this with me though) and It will have the voltage locked at 1.274v and the core at 1420 MHz it has worked so far for me flawlessly. I do get crashes in games but that is everyone who is running 355.98. Right now the drivers are sooo bad.... Go check it out in the GeForce forums.
 
P.s. if you do flash this bios do not touch the overvoltage slider if you want to manually clock it. (disable overvoltage in precision x)

I'd prefer to edi my bios, as it's a newer version; what I was asking is which is the maximum safe voltage for my card, and the max safe power limit...

Ah I see. There we go PM Sajin and see if the one that is made is safe to flash on my first post. If not he will gladly help you on maybe making one :)

gpvecchi
Guys, I'd like to edit the bios of my 980 Ti Hybrid, to achieve the followigìng:
Max safe voltage (I assume first slider to 1.281)
Max power limit and/or TDP (I assume 75W+75W+150W, even if my bios seems higher for 6 pins)
Keep stock boost, and stock at default values of PrecisionX, but maxed when moving the sliders...
Could someone suggest me? Thanks!

You're correct. You can edit your own vbios using maxwell bios tweaker v1.36.