PCI Express & CrossFire: Scaling Explored
Test Results: Crysis, GRID, And Supreme Commander
Crysis gets no additional performance from CrossFire mode at low details and resolutions, but increasing its resolution to 2560x1600 allowed the high-end X48 Express to shine. Notice that these benchmarks fall almost directly in line with PCI Express bandwidth for a single card.
The CrossFire performance advantage is much easier to see at very high details, with both the X48 and P45 playable at medium resolutions. Adding a second card actually hurt P965 and P35 systems in Crysis, with a performance loss exceeding 50% at 1024x768.
Race Driver GRID had an odd issue where the system would occasionally hang while loading if the graphics resolution and details were set too high. If we waited long enough for everything to load, we would experience a sudden increase of up to 1000% in frame rates, but at 2560x1600 pixels and high details our systems would only load approximately one out of every ten attempts. Thus, while we were able to test low details at 2560x1600, we were forced to limit our high-detail maximum resolution testing to 1920x1200 pixels.
There’s no need for CrossFire with GRID set to low details.
CrossFire provided GRID a big performance advantage at 1920x1200 pixels and ultra-high details, where the bandwidth of the P45 Express chipset’s PCIe x8 2.0 mode slots put it ahead of the 975X’s PCIe x8 1.1 slots.
Supreme Commander Forged Alliance gets a big boost from the 975X motherboard’s overclocked memory controller, but more important was the gain that every motherboard showed from enabling CrossFire. Strangely, the PCIe x4 1.1 secondary slots of the P965 and P35 Express motherboards had little adverse effect in this game title.
Enabling higher visual details has little effect on the leadership positions of various motherboards, with the 975X’s higher memory bandwidth still keeping it in the lead and the x4 secondary slots of the older mainstream boards having very little negative effect on the CrossFire performance advantage.
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sparky2010 should've included 1920x resolutions in the last page, as there are a lot of people out there with screens capable of that resolution.. but anyways, all in all a very good and informative article.. but i'm going to settle with a complete makeover when core i7 becomes more available!Reply -
V3NOM yer kinda interesting to see how things have changed with new mobos but it doesnt really have any practical value tbh.Reply -
Crashman V3NOMyer kinda interesting to see how things have changed with new mobos but it doesnt really have any practical value tbh.Reply
It's all about answering the question "Will a second card do the job".
Lots of guys have midrange or better ATI graphics cards, and the question of "upgrade or replace" is constantly being asked. -
outlw6669 @ arkadiReply
Yes the x58 is out.
However, as it can not be paired with a Core 2 CPU and runs DDR3 exclusively, you can not directly compare the results.
In general, I would assume crossfire on the x58 will scale similarly to the x38/48 as they both have the same PCIe configuration. -
Crashman outlw6669Thanks for finally getting this review out!Reply
It was planned for September but kept getting delayed due to tight deadlines on other articles. But when the economy finally went from a slow decline to a nosedive in November, we knew this article had to come out right away. More people are putting new systems on hold and looking for ways to keep their old ones up to current performance standards, and we care about upgraders just as much as system builders.