CrossFire Scaling Analysis
While a two-card CrossFire configuration generally benefited the P55 platform almost as effectively as it did the X58-based platform, we saw mixed results with a third card added. Poor bandwidth on the P55’s third slot caused triple-GPU performance to actually go down in some benchmarks, dipping below the dual-GPU and occasionally even single-GPU results. Yet, by adding in a few successful benchmarks, a chart of average performance doesn’t reveal this weakness.
Looking only at averages, the chart above makes it appear that adding a third card boosts P55 performance by nearly 8%. Yet the fact that it hurts performance in some games and offers no benefit in a few others means that we’d never suggest using the P55 PCH to host a third graphics card in CrossFire or SLI. Moreover, the X58 gains 25% by adding a third card and has no performance issues, with the exception of the well known Crysis “2560x1600 plus AA” multi-GPU bug, likely caused by our cards running out of frame buffer.
We again see that this particular X58 motherboard is slightly slower than this particular P55, as demonstrated in the single-card tests, and we refer back to its earlier review to prove that the difference is limited to this specific motherboard model. Yet, even though our motherboard of choice is slightly slower than many others, its dual-GPU CrossFire configuration provides 4% better performance than the P55 with identical graphics.
