Windows 7: A serious unknown error

I bought my computer less than a year ago from Best Buy and after 30 days I bought it I notice serious lag, sound crackling, and sound buzzing at the same time. This happens when I am playing "demanding" games suchs as fallout 3, crysis, call of duty 4, bad company 2 etc.., though it happens more in game than the other and it sometimes happen when I am just listening to music. When I go into event logs, there is no log on the problem that I am having during the time of the incident.

I think it is a hardware related problem because a few months ago, I reformated my computer to see if it was a software-related problem but it was not. I know that it's not my video card because I used 2 different video cards and the problem still occurs. The whole thing started when I installed Bad Company 2 in the first place but I don't have it installed anymore. my computer is still under warrenty but Acer won't just let me send it the computer without me telling them the problem, but I don't really know.

The only thing I can think of that's causing these very annoying problem is Windows 7, my motherboard, my power supply, ram, my processor, and/or computer dust.

Computer specs: Acer M5802 desktop
Windows 7 Home Premium x64
8 GB DRR2 RAM
Intel Core 2 quad Q8400 2.66 ghz
750 GB HDD
*Nvidia Geforce GT 220 1 GB* (OEM)/ ATI radeon HD 5770 1 GB

*NOTE* the GT 220 came with the computer.

Sound--, check your audio card and driver.

I have the lastest sound driver and stuff. Even if I disable my sound card, I can still see the lag happening. I googled about this problem and i think 2 peple have the same or similar probem as me and we all 3 have Acer M5802

i'll try to get a sound recorder and record it so I can let u guys hear how it sounds like when it is happening, it's pretty intense especially in call of duty 4.

Try in safe mode. During boot hit f8 rapidly and quickly.

If that does not work
Try this
How to troubleshoot a problem by performing a clean boot in Windows Vista or in Windows 7

We can determine the problem depending upon which works, if any.

Am I able to play games in safe mode or in clean boot? Because that is the easiest way for me to see if the problem disappear and it happens like around 60% of the time when I am playing games.

You will be able to, in clean boot. Try safe mode and find out

safe mode dones't start up. on the internet it says to press F8 before u see the windows splash screen. I tried pressing F8, holding F8, and spamming F8. It just makes a werid sound from my computer.

F8 during boot press quickly and rapidly Do not jut hold it. Rapidly hit it.

If it does not work, use the clean boot as I mentioned.

Actually, if you go to msconfig ( click Start, Run, and then type in msconfig and hit Enter) the system configuration utility box comes up.
You should see several tabs across the top. One of them, when selected, has, in the middle of the page, a box you can check that says "Safe Boot". . check that box, and then click Apply and Ok and it will prompt you to restart the computer. .
do this, and then it will boot up in Safe Mode. .
????Can we do this Richard