Question unstable/slow 3950x

Jun 3, 2020
I have noticed that my machine has been running very sluggish in recent weeks and noticed in that in the BIOS my xmp profile for 3600 keep disappearing and I have to reset it. Then today it wouldn't restart and i had a "15" post code so I reseeded my RAM but I still couldn't get my XMP to stick. I then played around by mixing and matching the sticks in different dims slots, reseeded the 3950X and eventually i got it to both boot and keep the ram at 3600. I then ran cinebench and noticed my score was 1000 points less than I normally get. Restarted and saw the XMP went away again. Eventually i got it to stick again and ran cinebench and again i had the low score. So i ran my standard 4.3 ghz 1.3 v overclock that runs totally stable normally while edit or run cinebench (i would get scored 500-600 more than normal, but i normally dont keep it there) and now it crashes the machine when i run it. I have no idea whats going on so any help here would be very much appreciated.

Noctua NHU 12A
X570 Taichi
4x16 gskill ripjaws v red 3600
MSI Ventus OC RTX 2060 super