Have to reinstall Nvidea drivers very frequently, how to fix?

Hello, I got a new graphics card for christmas (Nvidia GTX 550 ti) and although it has been great most of the time, after putting the graphics card (and a new PSU) I installed the drivers off a disk and then updated them to version 310.70 from the official Nvidia website. This worked great for a few hours, but then I suddenly started to get very stuttering gameplay, dipping from the normal 60 fps to about 10 and then back up to 60 again every few seconds, mostly when I looked at new things in a game. I tried re installing the drivers again, and it worked fine. Then I turned off my PC for the night and when I started it up again I was getting the same problem. I tried searching for a solution, and tried using driver sweeper then installing the latest drivers again, but after a few hours I got the same problem. Re installing the drivers takes about 10 mins every time, and is getting quite annoying, so I am looking for a solution.

PC specs:

OS: Windows 7 64 bit
Processor: Intel i3-2120 3.3Ghz
Gfx Card: Nvidia GTX 550 ti (upgraded from Intel HD Graphics)
PSU: 600W corsair (upgraded from 240w)
RAM: 8Gb