Unable to download driver for AMD graphics card

So I've just installed a graphics card(AMD Radeon HD 7850)and after I did so the screen is all glitchy and it turns off into a black screen after a few minutes of use, I suspect it is because I don't have the driver installed but every time I try to install the driver it shuts down before I can download it. I'm hopping there is some way for me to get the driver on there without downloading it, however I have not found it. Thank you for reading this and hopefully helping my situation
 
Is the screen still glitchy if you use SAFE mode?

"YES" - bad video card or cable or connections

"NO, everything works" - download and install driver - but be very careful you get one which works with your card, I have heard the most recent Crimson may not.

Also, note that you may need TWO 6-pin connectors for power and your PSU must be strong enough (>500 watts)
 
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Is the screen still glitchy if you use SAFE mode?

"YES" - bad video card or cable or connections

"NO, everything works" - download and install driver - but be very careful you get one which works with your card, I have heard the most recent Crimson may not.

Also, note that you may need TWO 6-pin connectors for power and your PSU must be strong enough (>500 watts)

Everything works in safe mode but when I go to download the drivers the disk that it came with says it failed to find the detention driver and the Crimson says it's not digitally signed. And yeah, my psu is above 500wats
 
So it is probably the driver...but I doubt the one on the 4 year old CD is the answer. Don't know what a 'detention driver' is. Maybe someone else can help with that.

Download a more current (signed) driver from AMD. In the bunch labeled "Radeon™ R9 200, R7 200, R5 300, R5 240, HD 8500 - HD 8900, and HD 7700 – HD 7900 Series" at https://support.amd.com/en-us/download
 
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