I know its not what you asked for but I went with the Fractal Torrent in mat black with solid side panel and no rgb. Best case for airflow I have ever owned. Pure air cooling.
The only other thing that I noticed in the pics was that your gpu is only using 82 when gaming, so there may be some sort of power/thermal throttling happening.
I own the Fractal Torrent and this case seems to be designed like it with the 2 huge 200mm fans in front. If its anything like the Torrent then this case is gonna have some the best airflow on the market.
https://www.microsoft.com/en-us/Useterms/Retail/Windows/10/UseTerms_Retail_Windows_10_English.htm
If you live in the USA you do not own the product, just a license to use it.