Monitor Display Crashing/Turning one colour/Displacing

Hey there,

I've had this computer for about 1 and a half years after ordering it of PC specialist.
About 2 weeks ago after going to a LAN with my computer (i49 in the UK), my computer starting having a lot of graphical errors, where the screen would split so that the right side of my screen would appear on my left, and what normally would be the left edge of the screen would be somewhere in the middle of my monitor, and there would be a lot of static sometimes. If I move my mouse off the right edge of my monitor it would appear on the left on what should be the right of the screen. Or the screen would suddenly turn one colour, and I wouldnt be able to do anything apart from wait for the display to go back to something semi-normal or just restart my computer. I'm having trouble of getting a picture of this as when I take a screenshot, or stream my monitor display, it doesn't show any of the errors at all. (SEE IMGUR LINK AT THE BOTTOM)

My monitor display hops around between the problems above, I think when I start doing more intensive things, like playing games like Starcraft 2 and League of Legends, it increases the chance of the display crashing. The only solution I have found so far is to restart my computer (sometimes by just holding the power button if the screen is one colour and doesn't change back to a semi normal display after a bit).

On startup the screen is back to normal, but then it always starts happening again, sometimes after only 5 minutes of using my computer, sometimes after an hour.
I've tried using a friends monitor and the same thing happens, and I tried using a different VGA cable, and the same thing happens, so it isn't my monitor or VGA cable that is the problem.
I've also tried rolling back my graphics card drivers, and updating them, to no avail. All of them are up to date now.

Specs:
Processor (CPU): Intel® Core™i5-2400 Quad Core (3.10GHz, 6MB Cache) + HD Graphics
Motherboard: ASUS® P8H61-M LE/USB3 (NEW REV 3.0): M-ATX, USB 3.0, SATA 3.0Gb/s
Memory (RAM): 4GB SAMSUNG DUAL-DDR3 1333MHz (2 X 2GB)
Graphics Card: 1GB AMD RADEON™ HD6850
Power Supply: 450W Quiet 80 PLUS Dual Rail PSU
Operating System: Genuine Windows 7 Home Premium 64 Bit

Screenshot of what is happening:

https://i.imgur.com/SLptvCj.jpg[1]

This is a very confusing image. I'll try and explain what is happening. So this is a screenshot of my display - which does not show anything weird happening, but weirdness IS happening. In the screenshot, I am running OBS and pointing a webcam at the screen. Now in the webcam image, you can see my taskbar ( I have it vertically on the left side of my screen) in the middle of my monitor display, if you look at the top left of the taskbar you can see the minimize, maximise, and close program options that should be in the top right corner of my display. After taking this screenshot I started running more programs and trying to tax my computer so it would glitch a bit more, but it just went one colour and I had to restart my computer.
Do any of you know what is causing this problem, or how to fix it? I realise this post is pretty confusing, sorry about that. Thanks in advance!

This is what it says about my warranty - "3 Year Standard Warranty (1 Month Collect & Return, 1 Year Parts, 3 Year Labour)".

The 1 year parts warranty has run out, all I have is the 3 year labour now, not sure what the means though?

I've tried taking out my Radeon graphics card and running my computer just of the iGPU like you suggested, and everything seems to be working fine as I am typing this to you, although sometimes problems didn't show up for 10-20 mins after startup so I'll wait and see I guess.

Yep, so I've been running it off the iGPU for about an hour now and everything is going smoothly! After some optimisation I can still get around 40 fps on LoL so this is a fine temporary solution I guess. I also reseated and de-dusted the 6850 when all this started happening. I haven't used either of the programs you said in the edit, I assume they are to overclock my GPU or something? I haven't done anything like that to it.

In response to reinstalling the 6850, my hard drive stopped working in (I think) an unrelated incident last week, and made the computer freeze on the Windows loading screen on startup. I got a guy to repair it, but he had to wipe my harddive, so he did a fresh instalation of Windows and installed all my drivers and such. The graphical problem was happening before this, and still after (hence the post), so would installing my GPU again do anything different to what has already been done a week ago? Because that would have affectively been a clean install ?

I did use a program to check the temperature of my GPU, called HWMonitor. It showed the temperature of all my cores as well and such. The GPU was running at 30-31 Celsius and didn't change from around there, so I don't think overheating was a problem. Thanks very much for your help in all this! I posted to quite a few different forums, and you where the fastest responder and the most helpful by far. Many thanks!

Quite certain about the fresh Windows, the hard drive was completely wiped when I got it back, apart from the necessary drivers and other tat you get with a fresh installation. All the users had been wiped as well, I only have 1 user now and haven't got round to setting up a guest acc.

Any advice would be greatly appreciated, if its not too much trouble!