stew2

That tool is really very simple. Download the installer and run it. Then you double left click on the icon it gives you and it opens a screen with all you temperatures and fan speeds etc. You can then look at the readings and see if anything in your pc is running too hot.

By what you've described i think your graphics card is dying. I had the same problem with my last graphics card with little blue and yellow dots appearing and eventually it just stopped working completly.