Hi guys, I started building my pc awhile back, but life knows how to ruin your plans and so i had to stop midway..
I currently have,

Fractal Design Core Arc 3000
Intel i5 3570K Quad - stock cooler
Asrock Z77 Pro3
4gb ddr3 corsair xms 1600
SSD 120gb Crucial
PSU 650w


Now with this in mind, if I invest on a GPU will i be able to run AC with the build as is?

Money is still tight at the moment, so I got some trustworthy used GPU's ads to decide from, wich would you choose?

Beeing a r9 290 for around 200€ , a 7970 for around 180€ or a r9 280x for 170€ , all with warranty

Also, i plan to buy another 4gb of ram, it goes for 45€ or so, so I would rather buy it after the Gpu