MultiGPU Update: Finding the True Halo with 4-wayby Derek Wilson on February 28, 2009 11:45 PM EST
- Posted in
What We Couldn't Cover
Our tests will include the GeForce GTX 295 Quad SLI, GeForce 9800 GX2 Quad SLI, Radeon HD 4870 1GB Quad CrossFireX, and Radeon HD 4850 Quad CrossFireX. We were unfortunately not able to test the 4850 Quad with 1GB per GPU because we didn't have 2 of the 4850 X2 2GB cards. This would undoubtedly have made the 4850 look a little stronger in Quad at 2560x1600 (where it really counts). While it wouldn't compete for the highest end performance, the higher memory Quad 4850 is certainly of interest to us after seeing the value in two of them. But we really don't expect any Quad option to deliver on bang for buck metrics.
Past that, we also didn't include Race Driver GRID this time around. Due to our continuing issue with FRAPS, we couldn't record performance data for either of our Quad NVIDIA solutions. We didn't feel that presenting the data from the game with just AMD hardware was highly useful, but it is worth mentioning that just looking at the numbers we could tell that the Quad NVIDIA solutions performed slower than the AMD solutions. I do apologize for a lack of quantitative data, but sometimes that's how it goes. We will continue to try and collect this data and we may do something with it down the line if we are successful.
Our first article explored 1 to 2 GPUs. The second looked at 1 to 3 and 2 to 3 GPUs. This one only focuses on the performance improvement from 2 to 4 GPUs. The reason for this is that there are no single GPU versions that exactly match half a GTX 295 or half a 9800 GX2. We can see when things don't scale and how they scale differently from 3 way by looking back at the previous article if people want, so having a lopsided analysis that included some metrics for AMD and not NVIDIA didn't seem quite right.
Just like the diminished returns we saw when moving from 2-way to 3-way, we see more diminishing returns when moving from 3-way to 4-way. The way we can get a feel for that more directly is that we see much less scaling when moving from 2-way to 4-way than when moving from a single GPU to two (even though the theoretical performance improvement is the same).
This time around, we didn't zero the value data when performance didn't meet a threshold. We know some people liked that way of doing it, but value really isn't a focus of a 4-way GPU shootout anyway, so we feel that the data is more academic on its face. This article rounds out our data and has all the performance numbers for all the parts we've looked at, while our analysis focuses on 4-way. We are still actively refining our approach to representing value moving forward, so your feedback is not only welcome, it is greatly appreciated.