I had a problem recently with my laptop as t only gave me 3.2 out of 8GB available, the other 4.8 wer ereserved for hardware. I switched the RAM bars (2x4GB) and suddenly it gave me access to my whole RAM except for 800MB which is fine.
So I fixed this on saturday and have been using my laptop normally since then. However today when I wanted to us it I noticed it was really slow and that the frame rate in a game I played yesterday night without problems hda dropped to between 5 and 20 FPS. I did not install anything or update any drivers since yesterdat.
I am not much of an expert with this so please let me know what information you need or if I have to run any diagnostic tolls and post the resultats.