NOTE: these are the settings I use with my system, I7 6700K & Nvidia Geforce GTX 1080, With a system as  powerfull as mine you can max everything out , however P3D is still a 32bit application and you will run out of VAS soon enough and encounter OOM. In this blog you can find the settings i always use for IFR flying and I never run into OOM even with payware aiports, scenery , textures and aircraft on longhauls. ATM i use AS16 for weather engine, ASCA for clouds and Envtex for sky and other effects and to top it all of PTA ofcourse.  I DON’T use REX4 nor Soft clouds anymore

People should know that some settings are very CPU bound like autogen & traffic for instance , while Texture resolutions and shadows and FSXAA, MSAA and so on are very GPU bound. If you got a powerful enough GPU like i do you can pretty much max out those sliders. Gpu bound settings will NOT influence your VAS as it will use the Video memory of the graphics card and not the system RAM. I highly recommend everyone to have a look at the P3D guide on Avsim .

AVSIM Prepar3D guide 

P3D V3.4.22

FTX Global Light Configurator

ASCA settings

Envtex settings

Ultimate Traffic II settings

ORBX Vector

Nvidia Inspector

PTA preset