Well, in the upcoming 6-7 months I am going to upgrade my GPU (R9 255, comparable with R7-something) to a higher end GPU, so should I go with the ATI/AMD R9 290X or NVida GTX 780? Or any other suggestions?

so i currently have the gtx 970 and i love that card to bits, so i can definitely recommend it.  

If it's going to be in several months time, you might want to wait for AMD's new GPU series to come out. Then, if the series is great, you can get one of those.

However, if you're getting it soon, I'd recommend the 290x (like you said) or the GTX 970. The 290x is hotter and uses a bit more power, but is cheaper and sometimes runs better than the 970. Also make sure you have the right power cords from your power supply.

If it's going to be in several months time, you might want to wait for AMD's new GPU series to come out. Then, if the series is great, you can get one of those.

However, if you're getting it soon, I'd recommend the 290x (like you said) or the GTX 970. The 290x is hotter and uses a bit more power, but is cheaper and sometimes runs better than the 970. Also make sure you have the right power cords from your power supply.

​I was going to wait until the 300-series is released because hopefully the 200's will drop a couple of bucks in price.

Yeah, uhm, so I made some research, and well, to be honest the situation looks shitty for me. My PSU is on 500w, and well, it's gonna be strained running some cards.

Looks like if I am going to upgrade my shit, I'll have to get a new PSU and a new case ontop of that because mine is tiny. 

 

So, I am broadening my mind into other cards that not too big or too PSU heavy.

well you can pick up a 750W PSU for cheap(75$) and the same GPU i have the R9 280X 3GB and it runs about 250$ for both just some options i mean i had before this card a 770 Superclocked and it constantly overheated so i wouldnt recommend it. Look at options that you want, the computer is yours and your going to want it to run smooth, so do what i did put stuff into a cart till i found the right price range. Good luck in your search