Computer Game On and Off Lagging

[gsbkho]

Hi Guys
I'm new to the forum here so I would appreciate if you guys would give me any feedback regarding posting and stuff 
I'm also not that experienced in computers so please explain things to me in more simple terms  .

So basically I have a problem with my 3 year old PC. It has been an ongoing problem since about one year ago I think. Basically the problem is that whenever I try to run video games ranging from minecraft, to StarCraft II, my computer starts to lag. When I first run the application, it works OK for around 5-10 minutes, however at a certain point, my computer starts to lag by a lot. The frame rate is horrible, it gets so bad that I just can't play the game. I find that if I minimize the game and wait for about 5-15 minutes, the lag will stop and the game will go back to running smoothly. In fact, the game runs much better than the first 5-10 minutes before the initial lag. Then, after a time period of around 15-30 minutes the game will start to lag YET again and the whole process starts all over. I've ran virus tests with Avast Anti Virus, defrag, changed graphic settings to very low, shut off all unnecessary start-up programs, and I still find that the problem persists. When I open the windows taskbar I look at the physical memory being used before and during the lag and it stays around 20-30 percent while CPU usage only goes up to 60% max. I don't think anything is wrong with the fan/cooling system either. One other note I noticed is over the summer I had been away for 2 months and when I came back the games actually ran fine for about a week. Then the lagging started to happen again. It could be the fact that I had turned my computer off for those 2 months when during the time I"m home I generally don't. I'm not sure what is wrong so can someone please help me!!!! I am completely at a deadend at what to do.

I am using Windows 7 Home premium and
My Computer Specs are:
AMD Phenom(tm) 9750 Quad-Core Processor 2.40 GHz
8 GB RAM
64-bit Operating System
 Thanks Guys!

[geek hoodlum]

Hi and welcome to Computer Hope!

In order for someone to help you diagnose your problem, they are going to need as much information about it. Detailed is much better.

What hard drive do you have? How big is the hard drive? How many free space do you have in your hard drive?
What video card do you have? How big is the memory of video card do you have?
Did you add any new hardware to the system? If so, what?
Did you install any software? If so, what?
Are all games you mentioned are genuine? (licensed software)
How about playing the game while your anti-virus program is disabled, do you still encounter lag?

[gsbkho]

I'm not sure where to find the info on my hard drive but I think its ST375052 8AS SCSI
Size: 699 GB
486 GB free
My video card is NVIDIA GeForce 9100
The total available memory is 3840 MB, dedicated graphics memory is 256 mb, dedicated system memory is 0 mb and the shared system memory is 3584 mb

No new hardware installed
New Software- Windows 7 ( I used to have Vista)
All the games I've mentioned are genuine

[geek hoodlum]

I've ran virus tests with Avast Anti Virus

What is the result?

Are you connected also to the Internet while playing the game? There are programs update automatically specially when you are connected (but depends on your settings). There's a minimal possibility that your game will lag while some programs are updating at the same time .

Anyway, let's wait for other Computer Hope experts to analyze and give you advise.