Adding even more value to the Radeon HD 5830 is its overclocking ability, though this is still a bit of a gray area right now. Although we were able to reach a core clock of 900MHz and a memory clock of 1300MHz, it appears that AMD is limiting overclocking performance at the BIOS. Already this small overclock provided us with performance gains as high as 17%, but imagine if the core could reach 1GHz.
At this stage it is not clear why AMD is limiting the overclocking performance of their graphics cards. Perhaps they are trying to avoid the throttling issue that we found when testing early samples of the Radeon HD 5970, though this is not an issue we have found troubling their single GPU solutions. Honestly, we have no idea why AMD are doing this, as it makes very little sense to shutout the enthusiasts.
The 125 5770 your using in this argument, (really 135 sans rebate) does not have eyefinity available also with its 512 memory would run in to trouble over 1920x, but yes it would be powerful. If the prices fall like this
The 5770 1gb is 150$. The 512Mb is 125$, and when you use then in xfire, you end up with 1gb of memory.
not how it works at all, you don't add the mem together since one card can't reference the memory from another
also look at it this way, if you use AFR (alternate frame rendering) each card has to have a copy of the scene in memory (albeit at game times) so each one would need its own memory to render the scene
spend the extra $25 ($50 for 2) and get the 1GB models
keep in mind 512MB might be enough for now (1680x1050 and lower), but games use more memory overtime and having 5870 speed with 512MB per GPU could cause it to render a lot slower in the future