Crossfire: does it actually buy you anything?

I see that NewEgg has my graphics card on sale for $99. ATI 4870. I already have one in my PC from a couple years ago and I am wondering if getting another and hooking them up for crossfire will actually do anything to boost performance.

http://www.newegg.com/Product/Produc…-376-_-Product

I'm not sure exactly how it works these days, but I know that the benefit won't be consistent. Some games will take advantage of the second card, and some won't.

However, Tom's Hardware seems to suggest some quite healthy boosts, so it's truly up to you and if your PSU can handle it.

Wow! Those do look pretty impressive.

The PS is not an issue as when I built this thing I put in a 1000W supply.

Can I plug my refrigerator into your power supply?

Sure, bring 'er right on over.

When I built the system I was going to get a smaller one but the 1000W version was on sale for the same price. I do have a lot of things stuffed in it including 6 disk drives and 2 optical drives.