Dell Studio 1745 - Very annoying long CPU spikes along with audio stutter every few minutes that last a few minutes.

I bought my laptop which is a Dell Studio 1745 in 2009. Since about 2011 or 2012 I've had this issue where whenever I play games where 50% + of cpu is used, every couple of minutes I would get immense lag spikes. These last up to about 5 minutes at a time and the computer is absolutely un-usable when this occurs. The audio stutters and it basically becomes static and the game I play starts running at 0fps (along with the system itself!) even though it normally runs at something like 60-120fps. Whenever this happened, in the task manager I noticed that the cpu was at a constant 100% spike for the duration of the huge lag and after the lag stops everything works as normal until the next big spike hits the scene. There are no issues with the memory usage, just the cpu. I noticed that a part of the underneath of the laptop is slightly hotter when the spike is occurring than when it isn't but there isn't a huge difference in temperature. I've tried many things like elevating the laptop slightly to allow it to breathe more but that didn't do anything, I also opened it up and got rid of some dirt wherever I could. I noticed earlier on that audiodg.exe was taking up 40+cpu at times so I got rid of audio enhancements and even though the audiodg.exe cpu went down completely this is still an on-going issue. I defragged, I did antivirus scans, I tried everything and yet this issue is still here and oh my god is it annoying. It makes games unplayable when the spikes hit ( my computer can run all of them no problem ) and it takes the enjoyment out of them, mind you some of the games I play don't require a NASA computer and they include simple games like Minecraft, Kerbal Space Program or Hearthstone. Here are some of my specs:

System: Windows 7 64bit

Processor: Intel(R) Core(TM)2 Duo CPU T6600  2.20 GHz

Ram: 4.00 GB

Graphics Card: ATI Mobility Radeon HD 4650

What I ask for is help and guidance but please don't suggest checking for viruses or defragging because I'm sick and tired of doing those things! Please understand my frustration with this issue as it has been with me for the past few years and I hope you'll help me resolve it.