..hopefully u guys can help me ...right im building my first computer and im just gonna run 1 hd4870 graphics card..now in the future if i wanted to use 2 hd4870 will i need 2 monitors for crossfirex to work or what how does it work?? or would crossfirex still work on 1 monitor?
2 cards, 1 monitor. Each card basically handles half of the processing, so in theory, you should get twice the frame rates. It doesn't work out quite like that, but it does help a lot. Of course there are a lot of other things to consider, for instance the resolution you run at must be pretty high to see the most benefit, just google, there is a ton of info, literally a ton of it around.
Yes, you can hook up 1 monitor. As a matter of fact, you can only use the output on one card when you use CrossfireX.
There is a Crossfire ribbon that you connect to both cards, and in the drivers you can either enable or disable crossfirex. The drivers is how the computer knows how to run 2 cards. Scaling is getting a lot better than it used to be.