Recently I replaced my CMOS battery with the same type(lithium 3v cr2032) . When I started the computer everything when fine.All I had to do was to set the "legacy diskette a" to disabled and fix the boot order .After Windows started I tried playing a game,which run smoothly before changing the battery (CoDMW3 SP) but after I started playing the fps went low around 19-20 and the sound was kind of crackling.The CPU and GPU temp were normal.The ram and cpu indicators were around 70-80% which is normal when I play games. When I am browsing the internet or doing sth else everything is fine, probably because i don't use that much resources. My motherboard is ASUS P5KPL-AM.I probably should change sth in the BIOS,causing malfunction, but I don't know what exactly .There is a download lnik for the MB maual with the BIOS description in the ASUS website (http://www.asus.com/Motherboards/P5KPLAM/#support_Downl...), but i have no idea what I should change.Now it is set to default(fabric) settings except the boot order and the floppy disabled .I would be pleased if someone knows and is willing to help me.
Try updating the bios. The CMOS battery really wouldn't have anything to do with your problems.
I updated it with EZ flash utility, but the problem still remains. The reason why I changed the battery was that the computer was losing its time and date settings every time i turned it on. Before changing the battery everything was fine. The games ran smoothly without lag and sound crackling.
P.S. I also noticed that when I watch HD videos the problem is the same.