I noticed that my 1080ti doesnt utilize its power limit as it should while doing some thermal tests since i have a morpheus lying around and wanted to experiment a bit with it. BUT even under 20 minutes of any load i could throw at it the temps never exceeded 60c in a about 20c room. The case has ok airflow so the card should be getting way warmer since the fans span at about 50% max. Checking GPU-Z it said that my Power Limit was averaging about 80%. I had everything stock at that time. The GPU boosted to max 1930 MHz and in Timespy hit about 8400 points so lower than it should.
 
My System:
8700k @ 4.7Ghz
16Gb of Ram @ 2666Mhz
EVGA z370 Classified K
EVGA Supernova 750 G1+
Playing in either 1440p @144hz or 2160p @60hz so shouldnt be a resolution issue
 
What i already tried:
Lifting the Powerlimit JUST IN CASE did nothing
Lifting the Voltage since GPU-Z said i hit the Voltage Limit GPU boosted a tad higher and the power draw grew a bit but still not exceeding the 90% Mark
Checking all settings in the Nvidia control Panel for Power settings aswell as the Windows Power plan
Reinstalling the Driver with DDU
Overclocking everything ( after 60Mhz+ on the core everything started lagging and crashing giving me 1980 MHZ max but still underperforming)
Tried playing with the memory speed if either over or underclocking did any good and nope it actually let the core drop the clocks to 1898
Resetting all things in Precision X and the same things with Afterburner after that. 
Tried the K-Boost button on Precision X 
Checked All the Powerconnectors
Also restarting a few times obviously
Even Furmark in 4k didnt manage to exceed the 62c mark tho it managed to let GPU-Z say power limit instead of the Voltage limit.
 
At this point i am really confused to what i could have missed. Note that the Card is only 3 months or so old and had never been OCd before that.
 
Any help and advise would be appreciated. (And sorry for the grammar ofc)
 
Attached are two GPU-Z screenshots after about 5 minutes of heaven in extreme in 1440p
 

New. I Actually won it directly from EVGA this summer. Shipped on August and arrived here in September. Hope that helps

I just tried to run the test a few times but the Graphics Test 2 never works so i just have the FPS for GT1. Always had problem with 3DMark :/. I am hitting 54.8 FPS there while the FE version tested by Guru3D already hits 61.56 meaning that its performing more than 10% worse in that test. 
The EVGA Precision X was set to 100 and i clicked on default twice before the tests. GPU-Z still claims about 75% AVG and the reported Precision power numbers spiked quite drastically from 60 to 115 i'd guess about 90 avg. there. 
Best regards
 
 
Source (  )

388.13 is one of the worst drivers you could be using. I'd recommend updating to at least 399.24.
 
To hit your max power limit I would recommend that you overclock your gpu to your max stable overclocks on both the core & memory, and then run unigine superposition on the 8k optimized preset. Doing that will definitely make you hit your power limit. 

On the stock vbios there will always be a performance limiter such a power, voltage, or temp.

Yep, I see what your problem is...
 

 
That should read x16 3.0 when under a load.