Solution
No, you can't do that. AMD CrossfireX Technology requires two or more similar GPU's and the 4850 is much older technology than the 7770. You can only crossfire a 7750 or a 7770 card with another 7770.
I don't think that this can be done in a reasonable way and even if it could, your computer would not be able to do DX11 gaming because the 4850 isn't DX11 compatible. This should be doable on a computer if you get a motherboard with a HydraLogix 200 chip and maybe one of a few other chips, but those are rare and usually expensive boards.

You'd need something like this:
http://www.newegg.com/Product/Product.aspx?Item=N82E16813130595
 

JKatwyopc

Distinguished
No, you can't do that. AMD CrossfireX Technology requires two or more similar GPU's and the 4850 is much older technology than the 7770. You can only crossfire a 7750 or a 7770 card with another 7770.
 
Solution
crossfire only works if the first 2 digits of the model match. the crossfire will take on the clock of the weaker card. I.e you can xfire a 6870 and a 6850, but the 6870 will downclock itself.

Crossfirechart-1.jpg

068d19bb_AMD_CrossfireX_Chart_1618W.jpeg

AMD_CrossfireX_Chart_1618W.jpg


cards below this is almost irrelevent
 

Cisco79

Honorable
Jun 9, 2012
3
0
10,510
Thank you all very much, I Google'd it and found nothing.... So I obviously it was impossible lol! Anyone got a 7770hd for sale? Playing bf3 on high with one getting 30-40fps, but I want a tad bit more...
 


That's what I was referring to.


Do you find HydraLogix funny? It can pair two of ANY graphics cards so long as one of them has an NF200 chip or the motherboard has an NF200 chip. Heck, you could pair a GTX 295 and a Radeon 6970 or some other wacky combination that way if you wanted to. The motherboard link that I gave has one such chip.