|Your 8400gs graphics card is not the latest and will be the limiting factor on many games. Try running them at lower settings and it may be tolerable.|
We cannot help you get your system set up right and stable if you do not post your settings and detailed hardware information. We NEED:
Was this a factory built system?_____ Make/Model_____
If custom or modified, list each item make/model:
Motherboard Asus model/version___________
Graphics: NVidia 8400GS 512MB
Power Supply make/model/wattage_______________
Plus all settings (from BIOS and/or CPU-Z/SpeedFan)
Plus current temperatures-internal (from BIOS and/or SpeedFan)
AND do not forget Vcore (voltage setting to CPU from BIOS) and other voltage settings.
With the information you have supplied so far, we are just guessing and throwing out ideas, since you do not know what is reasonable and what is not, you need to give us the tools to help you. Without the proper information, we cannot help you.
You have to be a little bit crazy to keep you from going insane.
This site is about helping people, lets keep it that way.