PC Perspective took an indepth look at AMD's Eyefinity and discovered that there are quite a lot of issues when you use CrossFire. These problems include interleaved frames, stepped tearing and dropped frames. One of the results of this is that the actual, observed framerate of Eyefinity + CrossFire is much lower than the benchmarked performance captured by programs like FRAPS. You can read the full report over here.
AMD responded to the article claiming that these issues are due to synchronization issues and claims they will address this in a future driver update. Lets hope they do because this issue also occurs on 4K monitors.
AMD continues to tell me that its “4K story” will be revealed and known to us very soon and that all of our questions will be answered. That very vague statement is meant to address the coming onslaught of stories about 4K gaming that requires the same Eyefinity technology we have been discussing here today in this article. Currently 4K monitors like the ASUS PQ321Q are running two screen Eyefinity / Surround configurations with dual 1920x2160 heads internally. As a result, everything we are seeing in our 5760x1080 testing today does carry over to 4K monitors and gaming.
As I mentioned on a previous page, AMD, as they have previously stated, is committed to fixing these CrossFire + Eyefinity problems for the upcoming generation of products and the current Radeon HD 7000-series of cards. Though much of the discussion is still going to be embargoed until further notice I have renewed confidence that the substantial Frame Rating issues with these configurations will be addressed, I just don’t know exactly when. For gamers that have already invested in this ecosystem of multi-display, multi-GPU hardware that answer isn’t going to appease them but it does make this information presented today easier to accept.