Computer is crashing alot.

I have a weird issue that has just started to pop up on my pc over the past couple of weeks, what happens is my monitor will go black and my cpu fan will die right out and then everything goes back to normal, then after about a half hour to an hour later, the cpu fan dies and i get a message on my monitor saying that i have no dvi cable connected, my cpu fan has also been running at higher rpms lately and im doing what i can for cooling. what could cause this?

There are several things that can cause what you're describing. It could be something as simple as dust build up, or it could be something major like a failing CPU, graphics card, etc. You could go through the steps in this troubleshooting guide that was prepared by one of the Forum experts.

Troubleshooting Steps for Windows 7

You could also provide information about your computer. At the top of every Forum page is a link called "User CP". Click on that and in the left column you'll see "Edit System Spec". Click on that and fill in your info. If you're not sure about your system specs, this tutorial may help.

System Info - See Your System Specs

You could also install a free program called Speccy that can provide system spec info as well as real time temperature monitoring for CPU, hard drive and graphics card.

Speccy - System Information - Free Download