CrossFire-X, eXplored
Conclusion
Here we finally see CrossFire-X scaling exposed. Two “mismatched” cards in FrankenFire do not default to the slower card’s speeds but the slower one generally contributes to the overall performance as the load is balanced between them as well as the drivers are capable with that particular game. We also saw some weirdness with the drivers in a couple of games where the results did not quite match up as in Crysis where HD4870-X2 gets unusually low frame rates in comparison to the other configurations.
Our Diamond HD4890-XOC has proved worthy of our “Editor’s Award” as it shows excellent scaling over the stock HIS HD4890. Now there is one thing to note, our cheaper HIS 4890 did manage to match Diamond’s overclock but the VGA fan needed to be kept near 90% to maintain stability in an overclocked CrossFire situation; and even at stock, the thermals were a bit high compared to the Diamond’s. Of course, your own overclocking results may vary radically from what we got and we did not volt mod nor use any other overclocking utilities other than Catalyst Control Center.
Our results are very consistent and we carried on where our Diamond HD 4890-xOC Preview, Part 1 and Part 2 left off. We saw Diamond’s overclocked HD4890-XOC coming on very strongly to replace the HD4870 as AMD’s top single-GPU. We also note excellent scaling over the HD4870 and even continued further good scaling with our very modest overclock. We saw the HD4890-XOC even trade blows with Nvidia’s now second-fastest single GPU, the GTX280. We are most impressed and highly recommend Diamond’s HD4890-XOC as offering great bang-for-buck!
As we move on to another review series – Big GPU Shootout – Revisited – we will continue to feature Diamond’s HD4890-XOC and also CrossFire and TriFire configurations, with many more video cards from each vendor. We will continue to bench with Catalyst 9-5, as that is the latest driver available to us. However, we will use GeForce 185.85 – the newest GeForce driver released since our last article’s 182.08. In this way, you can see the driver’s continued progress from each vendor and compare their performance directly from one driver set to the next.
We have noted some possible architectural differences between the HD4890 and the HD4870 beside core and memory speeds affecting performance in CrossFire-X. When we underclocked 4890 to 4870 speeds and paired it with a stock 4870, it still was a bit faster than 4870-X2 in many cases. And pairing “FrankenFire’s” HD4890 plus HD4870 in CrossFire-X against “true” HD4890 CrossFire showed much improvement when we were able to strongly overclock our older card. We also showed you TriFire results; our HD4870-X2 paired with the HD4890 and also the HD4870-X2 paired with the HD4870, compared – with the 4870-X2 plus 4890 pairing almost always faster.
If you are going to pick the most bang for buck in a multi-GPU configuration, overclocked HD4890 CrossFire should be your first choice. If you already have a HD4870 and especially if it is overclockable, you might consider pairing it with the fastest HD4890 you can find as this mismatched CrossFire-X pair comes reasonably close in a lot of the benches to “true” HD4890 CrossFire and is faster than HD4870-X2 or HD4870 CrossFire.
Our “Shoot-out Series” has been a steady progression examining Intel’s Penryn platform, and we have been upgrading it as necessary to maximize our PC’s gaming performance and to chart those improvements for you. Part IV, The Summary, showed this by comparing drivers all the way back to August 2008 when we first began benchmarking and focusing on the progress each vendors has made since then.
In our installment of Part III, Big GPU Shootout, PCIe 1.0 vs. PCIe 2.0, we especially focused on the motherboard’s effects on video card performance, using the extremes – P35 PCIe 1.0 vs. X48 PCIe 2.0. We saw how limiting the older motherboard’s PCIe bandwidth can be in certain situations and so we upgraded to X48.
Part II – The Big GPU Shoot-Out – Setting New Benches – demonstrated the need for overclocking our E8600 CPU from its stock 3.33 GHz to 4.0 GHz to take full advantage of our new video cards.
Part I, The Big GPU Shootout: Upgrade Now or Wait? we examined the performance of five video cards. We realized that the last generation’s video cards are not sufficient for today’s DX10 maxed-out gaming. Since our Q9550S review article, we now use Core 2 Quad Q9550S and recommend it highly! We also started to bench with CrossFireX-3 in Part I which ran on fairly immature Catalyst 8-8 drivers at the time and we have continued to chart its progress until now.
Stay tuned. We think we will have some very interesting articles for you to read as you plan your own coming upgrades. Well, we are done with our benches and this part of our series featuring Diamond’s HD4890-XOC in CrossFireX and we are already working on our next article. A new “Big GPU shootout – revisited” are in the works for you shortly – with many more video cards and game benchmarks than our original from last September. After that, we expect to build a new AMD PC and compare it with our current Intel Penryn platform featuring Q9550S at 4.0 GHz.
In the meantime, feel free to comment below, ask questions or have a detailed discussion in our ABT forum. We want you to join us and Live in Our World. It is fast expanding and we think you will like what you progressively discover here.
Mark Poppin
ABT editor
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