I currently have an HIS 5770 running on an ASUS P5Q3 with a C2Q 8200, 8GB DDR3 (yes, DDR3), and 750w PSU.
For whatever reason, I have a 2nd system engineering 5770 (unlocked/unrestricted) and it will not fire up on my mobo (or my son's ASUS mobo, but works fine on my other son's Gigabyte mobo, so I'm guessing it's some wicked compatibility problem). I recently got a pair of Gigabyte 5670s and before I tear my system down to *try* and put the 5670s in Crossfire, I was wondering if there will be any advantage to it. When I get another mobo, the 5770 will go in it in Crossfire or just be replaced in the upgrade. But for now:
Will the 2 1GB GDDR5 5670's in Crossfire outperform a single 1GB GDDR5 5770?
1 5770 is a much better setup, I havent seen the 5670 in cf I did see the 4670 in cf and the performance was good comparable to the 4870. the sme would apply. Micro stuttering would likely be an issue.
Just get the 5770 cheaper and the performace would be about the same or better as microstutering seems to be an issue. I have not seen it personaly but it seems to be a theme around here.
There will be no advantage to getting the two 5670's at all.
The 2 5670's would perform similar depending on title, but will produce more noise, consume more power, and produce more heat than the single 5770. Since you already own all the cards, it's up to you whether it's worth those trade offs or not.
A 5670 is really pretty much half of a 5770, with a crossfire on 2x 5670's you would get a 30-40% performance boost over one 5670 (depending on overclock). Compare that to a 100% doubled performance of the 5770, and you will see that there really is no contest, a 5770 will win every time.
Don't be fooled by how close the numbers in the name are, there is a lot more to a GPU series than that.
Stream Processors: 800(5770) vs. 400(5670)
Texture Units: 40 vs. 20
ROPs: 16 vs. 8
I think I got the answers I wanted, thank you all. A couple more things. I understand the 5670 is 'half' the card the 5770 is, but what about overclocking? Since I got them so cheap, I don't mind running them like a slut on prom night
Would that make up any of the defecits for the stream processors/TUs and ROPs?
I appreciate the replies, though they seem to be all over the place? Some say 2 is better, some 1. I already have the 2 5670's and the 5770, just a matter of whether to pull my 5770 and replace it with the 2 5670's at this point...