This happened to me on demo , and has started again with the full game it self now

this is copy pasted from my previous thread.

I installed crysis and i played it for about 2 hours , turn off my computer and go to bed, next
day i turn my computer on again and when i get on a server, my fps has turned from 80-120fps to 5-20 , i assume this is some bug with my computer, my computer is filled with stuff so decide to format it, after the format i launch crysis , yay everything works, then after installing some stuff i had to restart my computer, and crysis starts lagging again,

Does anyone have a similar problem , If so have you figured a way how to fix it? This is getting on my nerves.

GFX Card = PNY GTX 580
GPU = Phenom 955 3,2 quad core.
RAM = 12GB 1600MHz Corsair
PSU = Aero Cool 830W
Windows 7 64 bit.

One thing i did realize actually, is when this issue stopped on the beta , my sound didn't work.

I've got a Logitech G35 Headset.


Pleaaase i need help D: , This is starting to get on my nerves.