You'll have to forgive me if I am a bit vague so if you need more details please let me know.
As a PC Gamer I'm always trying new games to play and I just bought The Witcher 2 and hitting a brick wall realizing my computer could not handle the game even at its lowest settings, (despite it passing minimum required settings, but no follows those i guess). I also started to notice that some games have these FPS drops to around 4 FPS, like my computer is struggling to process everything. My computer is old I'll admit, but I never had a problem with Crysis on decent settings before or TF2 for example. Now from time to time while playing TF2, Portal 2 (on High Settings), SC2 (on high settings and only on the main menu), Dues Ex: HR (Fixed by lowering resolution), I get these FPS drops. They last for a few minutes at worst then everything was back to normal.
What confuses me is that I never really had this kind of problem before and I'm sure most the of the games i mentioned, (besides Witcher 2), are not too demanding of games.
If anyone has any suggestions as to what this might be and if I am able to fix it or not please let me know. If anyone needs more information let me know as well.
And thank you in advance for any help.
AMD Phenom 9550 Quad-Core Processor (4 CPUs), ~2.2GHz
NVIDIA GeForce 9800 GT