Hello there, I am the computer technician that will be assisting you today. My name is Norman-Wynne Damstra.
Welcome to Fixya, Miles Gordon.
This is a typical overheating problem. See, your computer heats up when playing games, in the first 5-10minutes. As the components get warmer they increase the air tempreature in your computer chassis. This heated air is insufficient to cool your Processor and Graphics card, therefore resulting in a Blue Screen of Death known as BSOD.
You are using the GTS240 Graphics card, it is a tiny tot so go easy on the detail settings.
Use the following settings:
Resolution: 1920x1080 if your LCD display supports it.
Anisotropic filtering: off
Set the rest to medium or low.
You will have to play arounf with the other detail settings depending on playability. If it's jittery set it to a lower detail setting.
Install 120mm or 140mm fans in your computer chassis if possible. You should at least have one installed on the side panel to provide freash cool air to the graphics card, processor and power delivery system ,MOSFETs. With an additional 120mm fan installed at the rear of the chassis to exhaust heated air.
Your power supply should be rated for at least 500Watts continuous power output, since the core i7 processor is rather power hungry.
to download Hardware Monitor, to check your tempreatures. Click download now, save the file to your computer and install it.
Your processor temp, should be nothing higher than 70degrees C and the Graphics card nothing higher than 75degrees C.