I have 4x8GB 1333 RAM and DCS 2.5 ran so poorly on my PC that I had to removed it - and I run P3Dv4 at 40 FPS and Il-2 at 50FPS and most games at 60FPS with most options maxed out.

I would suggest buying 64 GB RAM : 4x16GB

and a GTX1080 with a 1 TB M2 SSD as well.