Thanks, I found a XFX 5700 for around 360€ and I'm probably gonna get it...
Btw, I was thinking, seeing how I have everything apart from the GPU and the PSU, to hook up my old ones (RX 480 and thermaltake litepower 650w (shitty, I know, but it'll only be in for a week max)), and then when the new GPU comes to just ddu the old drivers and istall new ones.