Okay so one day when I was playing CS:GO I randomly got a black screen. My computer went to a black screen and as still turned on but I could not do anything or see anything. After I turned off the computer and turned it back on it was back to normal. However whenever I played a game it would do the same black screen thing after 5 minutes or so. After about a week of this it started to black screen no mater what you were doing. Then after that it started to act strange were if you clicked on the icons in the task bar they would not open and you could only hover over them (however if you did windows + shift + left arrow it would open). Also all of the shortcuts on my home screen were gone and when you would bring they mouse to the sides of the monitor the mouse would seem to travel off the monitor (meaning it would not stop at the edges).
So, I plugged my computer into my TV using a hdmi cable, I was previously using a DVI cable for my monitor. The hdmi cable was plugged into the main graphics card, not the on board one, so was the DVI cable. After I had hooked my pc into the tv it worked fine and almost everything was back to normal. The only change was that there was a cursor in the upper left hand corner and sometimes you could draw black boxes on the desktop.
Since this situation was not optimal I got a dell tech support guy over to my house and he replaced the graphics card with the same type. Sadly there was no change in the behavior. After that I figured that perhaps if I plugged my computer into my monitor with a hdmi cable it would work fine. However I realized that my current monitor did not have a hdmi port, so I got a new monitor that had a hdmi cable. When I plugged the hdmi cable into the main graphics card port on my pc and my monitor. The problem did not change and was just the same as it was before. When I made so that the hdmi cable was plugged into the on board graphics card the computer worked completely normally. Only problem was that I could not play games at 50 fps due to me using the on board graphics card.
Any ideas for what is going on and how to fix it would be much appreciated.
My theory is that it is a hardware issue with the on board graphics card connecting to the motherboard in a way that does not cause any problems. The only problem with this theory is that the main graphics card works fine on the tv.