graphics card problems

[Thewhitepanther]

i recently bought a pc whicH has A i5 gtx 660 2gb. My my friend is selling his graphics card which is the gtx 670 and offered me for £100 I have checked and my mobo can support sli but i need to know is it hard to install and is it worth buying .ie will two graphics cards work well.
obviously i will keep my gtx 660

 

[sixthshadow42]

i recently bought a pc whicH has A i5 gtx 660 2gb. My my friend is selling his graphics card which is the gtx 670 and offered me for £100 I have checked and my mobo can support sli but i need to know is it hard to install and is it worth buying .ie will two graphics cards work well.
obviously i will keep my gtx 660

You can't SLI with two different cards, you would either need another 660, or you would need to purchase 2 670's