Poor Preformance Thread

Hello Everyone!

I'll just get straight to the problem. Recently when I play any game after about a minute of play it just becomes unbearably laggy. Laggy as in, low FPS or not enough CPU or RAM to run the game appropriately. However, Most of the games that I play, such as BF3, Skyrim, and now Blacklight: Retribution have operated fine and meet the minimum system requirements atleast. I'm aware my PC doesn't get the best out of Battlefield 3, and can run Skyrim pretty well, but it shouldn't bog down like it has been. I removed some games when the problem first started and that temporarily fixed it.
However, temporary measures no longer work.
I also tested with a certain MMO, where if I run the game in the browser it works fine, but if I pull it up into fullscreen I get that insufferable lag.
I've also ran Avast! scans in the past which did not resolve problems.
Today I updated the Graphics driver to the latest BETA version available, and have been keeping it up to date. Obviously this didn't resolve the problem either.
I  have a few suspicious, graphics card going out, or the CPU going bad. Weather those are likely I don't have a clue.
Anyways here's the specs.

Manufacturer: Gateway
Processor: AMD Phenom(tm) 9150e Quad-Core Processor (4 CPUs), ~1.8GHz
Memory: 4096MB RAM
Hard Drive: 629 GB
Video Card: NVIDIA GeForce 9500 GT
Operating System: Windows 7 Home Premium 64-bit

The system is only a few years old I believe, and we upgraded the Graphics card from the original.
Unfortunately I am unable to discover what my Motherboard is. If the information is needed I'll need to be instructed on how to locate it.
Also sincere apologies if a similar if not the exact same problem has been posted before. My ignorance of the previous post would be the cause of this.

Any and all help is appreciated. Thanks.

Edited by: GooberTrooper