Multi GPU Technology Analysis – Nvidia SLI and AMD CrossFire Scaling, Frame-Time and Value Comparison
Conclusion: Parting words on Multi-GPU
In what was (hopefully) an interesting piece, we saw that high end AMD's offerings in CrossFire over XDMA have slightly better scaling, value and timings than Nvidia counterparts in SLI. We have also seen that the logical step forward for Nvidia's multi GPU technology is to reduce or eliminate reliance on the aged SLI connector or introduce a new version of the same - provided it wants to keep up with the superior scaling offered by AMD counterparts. Ofcourse, XDMA is just part of the equation; HBM (memory) is just as important and results in the elimination of one of the biggest bottlenecks in the entire work chain.
Pacal's test vehicles have already been spotted on Zauba, and the first flagship is expected next year. With Nvidia shifting to HBM as well, the gap between the scaling of both IHVs will change with Nvidia either catching up or even overtaking AMD counterparts.
If you are planning to go for a setup with multiple graphic cards, a dual Crossfire (XDMA) configuration of the R9 Fury X is a good buy, followed by a dual SLI configuration of the GTX 980 Ti
What is not good value however (for gamers) is the GTX TITAN-X, whose excessive price tags makes it have the worst value for money we have seen (probably exceeded only by former TITAN branded cards).
The multiple GPU scaling and deterioration was quantified to a reasonable extent and we were able to put a good cap on what a gamer (from any side of the camp) should expect with each added graphic card. It is also worth stating that with the advent of the DirectX 12 API, multi GPU performance and capability could take a huge leap forward. The included low level access would allow developers to get creative with how work is managed on the multiple graphic cards, improving a standard that has been historically riddled with problems.
Finally, I would like to add that the dual Multi-GPU configurations from both camps are a decent approximation (and an educated prediction) of the performance we can expect from dual-GPU flagships of both Nvidia and AMD. This means that fans of both hardware vendors can expect decent performance gains, which only leaves the problem of pricing - and that is something only time will tell.