So i have a
mobo: http://www.gigabyte.si/products/product-page.aspx?pid=2695#ov
psu: Corsair VS650
old broken gpu: ati radeon 4870 HD sapphire
new one: ati radeon 5850 HD Radeon + arctic cooler
Bought the gpu second hand, tested the gpu on his pc, also running a benchmark, everything worked...