Question Why are my Graphics so Broken?

[British Tanker]

Recently, my friend brought over a new graphics card to replace my old Saphire Graphics card 2008 Graphics card. I then proceeded to insert my new XFX R7800 series - 2009 version
I booted up my computer.....
and proceeded to realise that my screen was all squashed up (I changed the resolution and that fixed that) but It was still a bit squashed up, but the main issue is that I can't play just about any game. I can't play war thunder or Roblox before I could. I even tried inserting my old graphics card back in. I can play some very basic games such as Xmoto.
all cables are plugged in the graphics card and its in securely.
EDIT: IT IS FIXED:

 

[Ralston18]

Update your post to include full hardware specs and OS information.

PSU: make, model, wattage, age, condition?

Did you install the drivers for the XFX R7800?

Manually download the applicable drivers via the manufacturer's website. Install and configure for your build.

No third party driver installers/managers.

 

[British Tanker]

Did you install the drivers for the XFX R7800?
Right now I have the old one. none of them work.
specs: windows 10, intel i7 CPU and that's just about all I know. its built out of random stuff my friend gave, so I'm not quite sure what else.
it is quite old. its a rather old i7. about 2014?
I haven't downloaded drivers, but none of them work, when previously one of them did.

 

[British Tanker]

Power supply:
https://www.amazon.co.uk/gp/product/B00JKVHLIO/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1