What graphics card can i put in my computer?

none.

whys that its a new pc? any info would really help.

Supports PCI Express x16 graphics cards does this help.

bump

his computer has a 1 PCI Express x16 (Gen 2.0)

u can put almost any card
i have the same slot i put up 7870 XD its a great card can run everything at max !
u can use any card depends on ur budget  

but if u have a higher budget go for 7970 or 7950

hope this helps

go for any of these threee if u go lower u would still be able to run games but i don't know if could on ultra