I don't know if this the right board to post it, but to me it looks like the most appropriate. I have found a very good offer in my country to buy a PC which I think it can be turned into a gaming system but need to ask here as in this forum I solve all of my btc and computer related problems.
So here is the deal:
HP 8300 Elite
Core i7 3770 (done testing at game-debate , plays latest game with more than 100% at ultra high settings)
8GB Ram (is good as a beginning)
It has ATI Radeon HD7450 (a really really bad video card)
It is exactly regarding the GPU, can I add to this small case the GPU I like ATI Radeon HD7970 (it plays witcher 3 at ultra max settings at 93% testing done at game-debate)
I want to be sure about this before I buy it , the offer is very good only 429 Euro for such a HP 8300 Elite slightly used (while only the core i7 processor if you see at ebay is almost at 300 USD ).
Let me know if this can be turned into a gaming machine by adding the 7970 video card.
Isn't the 8000 elite and the 8300 SFF computers (Small form factor) which means they are tall but slim and may not hold a full length video card, you can try to see if you can find a video card that would fit inside (half sized) and you would need to change the mounting bracket on the gpu as well so it fits in the case.
the 8000, 8200, and the 8300 are the same size if I recall in the SFF versions, and do come with some decent quad core i7 CPU's if that was the config.
If you can actually get the video card in there and enough room for it to breathe then the cpu is fine and 8GB ram should be decent enough to start, I have seen some with 32GB RAM as its upgradable.
But check the specs on some of the higher end half sized GPUs first is my recommendation.
thanks!