Sent this to Hazaro to possibly be included in the OP, but gonna put it here for now. Exodu5, if you see any issues, lemme know if I missed something.
Who/What Crossfire/SLI is for:
-Running 3D Vision.
-Super high resolutions.
-Performance (not gaming) enthusiasts who don't care how much they are spending.
-Folks running a last gen card and want to extend the life on it by getting a second. This is only recommended for advanced users.
Who/What Crossfire/SLI is not for:
-People running a single monitor at 1080p or lower.
-Non tinkerers/enthusiasts. There are compatibility issues you will run into.
-"Futureproofing" your system.
-Getting two mid-low tier cards to "match" performance of a higher end card.
Q: But if X card is awesome, why aren't two X's twice as awesome?
A: Well, because for a game to really take advantage of it, there must be drivers to support said game. If not, you can run into performance loss, microstutterting, and all sorts of problems. In addition to that, there is generally a little bit of performance loss anyway, somewhere around 10-20%.
Q: Where can I find out more about Crossfire and/or SLI?
A: AMD's published information is fairly limited, but here is their website
. SLI Zone
has tons of information.
Q: If I have 2 1GB cards, does that mean I will have 2GB of video memory?
A: No, since both cards will more or less be processing the same data. In addition, it will scale to the lowest card you have in your system. So if you have a 1GB card and a 2GB card, you will only have 1GB of effective video memory.
Q: I'm not satisfied with the performance of X card at 1080p, why not add another one?
A: Well, for lower resolutions the technology just doesn't scale as well. If you have an older card, you might be better off looking at some charts to compare the newest cards with SLI/X-fire results of your current card. If there arent any, you can assume a 40-50% gain in performance @1080p, and a lower gain if your resolution is below that. This won't be 100% accurate, but it should give you a good idea.
Q: Can I use the same card from different vendors? For example, will an XFX 5870 work with an ASUS 5870?
A: Absolutely. Generally the only difference is clock speed on an overclocked model, or the design of the cooler. As with the memory, crossfire/SLI will scale to the lowest card.