CPU: i5 4690k
GPU: NEW R9 270x or used 280x or used GTX 670
RAM: 8gb 1600Mhz
Motherboard: Gigabyte H97 mATX (GA-H97M-D3H) or ASRock mATX (H81M-VG4)
Power Supply: a cheap one (for now)
Mostly I need opinions on the GPU. Would it be better to get a used video card or go for a new 270x.
The budget is max. 600€ but I can buy parts later as well.
I only need help on those items.
You already guessed it by now, but in case you didn't, this is my first time building a PC.