I really need an answer right now

My GPU requirement 

1.triple 1080p monitor gaming

2.Crysis 2,high setting,able to drive it at solid 60fps. ( Maybe above 30fps is good enough)

3. Not too expensive,keep it as low as possible.

First thing we need to know is, what do you consider too expensive?

And if you are going to be playing triple monitor in highj resolution you should get a card with a lot of memory.

No budget,just not going too expensive

I'm considering 7870,7950,or GTX 670.

those will play crysis on high setting/max on 1 screen. I'd say maybe crossfire 7950s or 670s in SLI those should play triple screen 1080p 50+ fps high settings it really depends on your budget though.

I'd personally go with dual 7950s over dual 670s because the 7950s offer more memory.

I'd doubt that the HD7870 will do the job but the 7950 is great for playing at high resolutions and so is the GTX670 so I'd definetly pick out of those two.

Little idea on how well the HD7950 does with eyefinity

Wait..what I meant at high is the lowest setting. The graphic settings in crysis 2 are high,very high,ultra. ( there is another one as I forgot what it is.)

In my country, 670 is only $25 more expensive than 660 ti. 670 is more expensive than 7950..by a few bucks.

in that case a single 7950 might out do a single 670 (3GB vs 2GB)