biggieweeb

For me every 3 to 4 years or if it breaks a couple years in i might upgrade

Ok i will look into it although im in the uk. I will check if they have that monitor in the uk

There is a similar element gaming qhd 144hz monitor over here in the uk for just over £200 and i watched some videos on it and apparently its pretty good. Im not sure though as i will have to save up for a few more months and i only have a 60hz samsung monitor with my 1080 system

Its possible that your power supply may not have enough wattage, im not sure, but i reckon for a 2070 super system i would go for a 750w.
When you are gaming your cpu and gpu may be consuming a lot of power and im not sure a 600w psu will be enough for your system.
 

The reason you cant bump your voltage up is because you are using a puny 400w power supply. For a gtx 1070 system you need at least a 500w psu. You GPU is being undervolted because not enough power is being delivered to it.

Probably as it has automatically undervolted itself and this would lower its performance. The fact that the benchmark shows 99% is irrelevant as the benchmark is using 99% of the AVAILABLE gpu performance.
Even if you think the problem is not the psu i would still recommend getting a psu upgrade, probably a 600w-750w psu. If this does not work, try getting the gpu R&D'd because the gpu may be faulty.
That is my theory on the problem.

If you still have the warranty for the cooler try and get it replaced