Possible to xfire a 290x and 290?

I was wondering if it were possible to xfire an AMD 290x and AMD 290 together using my corsair ax760i?

It can be done, but you'll get high frame latency if they're running at different clocks.

Couldn't he just overclock the 290 to compensate with the 290x? 

Yep.

Also if you do that it would be wise to put that one "290" in the 2nd slot so it gets more air. Or does it really matter " Someone "?

Hah nvm, I just had to install the drivers for each card individually and it worked from there on. Thanks for the feedback! :)