Avoid mixed CrossfireX.

So I have two HD 4870 512MBs in CrossfireX, and my roommate has an HD 4850X2 2GB. We decided to swap out an HD 4870 for his HD 4850X2 to try out triple CrossfireX. My Crysis Warhead performance actually got worse with mixed triple CrossfireX vs matched dual card CrossfireX. Just though I'd share that, nice little experiment for the day, I think tomorrow I'll check if my 3Dmark06 score has gone up or down.Avoid mixed CrossfireX.
I thought crysis doesn't scale well with multiple video card setups?Avoid mixed CrossfireX.
[QUOTE=''samuraiguns'']I thought crysis doesn't scale well with multiple video card setups?[/QUOTE]



Well, any games scaling is limited once you go from two to three. There is definitely a difference going from one to two with Crysis. In this case though, adding roughly another 1 billion transistors into the mix hurt the performance. I think the mis-matched cards are wholly to blame. Not only are their clock speeds mismatched, so are their memory interfaces. Something tells me if I had an HD 4870X2 I would have seen a boost.
I believe this is because crossfire limits you to the speed of your slowest card meaning that your 4870 would only be running at the speed of a 4850.So what you have is 3x4850's and that obviously isn't going to beat 2x4870's
Mixed crossfire downclocks to speed of your cards to the slowest one
Yeah turns out 2 HD 4870s can outperform 4x HD 4770s. Hopefully CrossfireX in the future will scale better passed 2 cards. HD 4770 CrossfireX Review.
[QUOTE=''PcGamingRig'']Mixed crossfire downclocks to speed of your cards to the slowest one[/QUOTE]



Bingo! If you mixing cards. Make sure its from the same family. I.E. an 4870 and a 4780X2 can be Crossfired without much problem. I believe Jiggly uses a 3870 and a 3870X2 in a mixed setup.
You guys are missing the point, I'm totally aware mixed CrossfireX doesn't work as well. I'm just astonished that the scaling is so bad that 3 HD 4850s don't even perform as well as 2 HD 4870s. That's my point.
[QUOTE=''Marfoo'']You guys are missing the point, I'm totally aware mixed CrossfireX doesn't work as well. I'm just astonished that the scaling is so bad that 3 HD 4850s don't even perform as well as 2 HD 4870s. That's my point.[/QUOTE]well also remember the HD4850 isnt near as capable as the hd4870also the mobo and cpu only support so many lanes. most are x8 x8 for two cards and x4 x4 x4 x4 for four cards some are x16 x16 and x8 x8 x8 x8.
[QUOTE=''washd123''][QUOTE=''Marfoo'']You guys are missing the point, I'm totally aware mixed CrossfireX doesn't work as well. I'm just astonished that the scaling is so bad that 3 HD 4850s don't even perform as well as 2 HD 4870s. That's my point.[/QUOTE]



well also remember the HD4850 isnt near as capable as the hd4870

also the mobo and cpu only support so many lanes. most are x8 x8 for two cards and x4 x4 x4 x4 for four cards some are x16 x16 and x8 x8 x8 x8.[/QUOTE]



True, true, I'm running PCIe 2.0 16x16 Crossfire BTW. Oh well, at least CrossfireX setup is easy, just install the drivers like usual, no extra steps. I haven't had any compatibility issues, so that's a plus, and I don't notice any extra stuttering due to adding a third non synced chip, so that's good too.

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