on my old titan with boost off 
everything simple for understanding
 

I flash my stock bios and have 2673score, but gpu work1576-1604mhz and voltage was 1576mhz-1.212v,1604mhz-1230v-sometime
1100mhz-by default1.005v

Check back in a bit I'm going to make you a better one. 

Maybe you need my stock bios i put here http://www.overclock.net/t/1573308/nvidia-gtx-900-cards-custom-bios-upon-request/1390
page 140, name-614318 ,980timy.zip-name bios,end of page

614318 here is a vbios made specifically for your card only...
 
980Ti-BenchX:
 
- 1.250v at load
- 425W at 121% - 350W at 100%
- Boost disabled.
- Boost locked to 1608MHz. 
 
All you should have to do is adjust power limit to 121% & set memory clock +493. Do not adjust the core clock it's already set to 1608MHz at +0. 
 
This vbios should also read correctly in GPU-Z. 

I will try thank you

You say 1.25 but in load 1.274v
2622score- do everything like you say
maybe trouble not in videocard 
it read correctly in GPU-Z 

Yep, there is nothing wrong with your card. I think you just need more overclock on your cpu.

Thank you for your help)

614318
Thank you for your help)

No problem.