Summary: Armed with an advance beta copy of Catalyst 6.10 and ASUS P5B BIOS, we set out to test P965 CrossFire performance and werenít disappointed: as we found P965 CrossFire to deliver equal performance to 975X under some games. Join us as we preview Catalyst 6.10 and chat with ATIís Godfrey Cheng about a wide range of topics including ATI physics and upcoming features that will be added to CrossFire in the near future!
But from here things get a little more difficult: what chipset should you pair your shiny new Core 2 CPU around? If you want to stick with a chipset from Intel youíve basically got two choices -- 975X or P965 (Intel has other Core 2-compatible chipsets as well, but for varying reasons these really arenít ideal for enthusiasts)
If you cared about ATIís CrossFire graphics technology, up to a few weeks ago the choice was pretty simple: Intelís 975X chipset. 975X is Intelís high-end enthusiast level chipset, and was the only chipset to support CrossFire out of the gate at Core 2ís launch. But 975X is an older chipset, and is limited to officially supporting just DDR2-667 memory. In comparison, Intelís newer P965 chipset officially supports both DDR2-667 and DDR2-800. DDR2-800 is capable of delivering 2.1GB/sec of additional memory bandwidth to the system. Peak bandwidth goes from 10.7GB/sec with DDR2-667 to 12.8GB/sec for DDR2-800.
Earlier this summer we ran some tests with a Core 2 Extreme and Core 2 Duo E6700 equipped with both DDR2-667 and DDR2-800 and found the faster memory provided an additional 2-4% in performance in games, while DDR2-800 shaved a few seconds off our DivX conversion and WME 9 tests in our media encoding testing.
Fortunately, most 975X motherboards offer a DDR2-800 setting inside their BIOSí, but officially this is considered overclocking by Intel/motherboard manufacturers, so youíll get no support if it doesnít work.
Another downside to 975X is that it utilizes Intelís older ICH7R South Bridge. ICH7 has been replaced the ICH8 South Bridge, which is used in the P965 chipset. ICH8 supports two additional Serial ATA drives (four in ICH7 versus six in ICH8) and two more USB ports (eight in ICH7 versus 10 in ICH8).
Arguably the biggest downside to 975X in comparison to P965 though is probably its cost. 975X motherboards typically sell for $50+ or more than equivalent P965 motherboards. When you consider the 975X chipsetís aforementioned deficiencies, and the fact that a lot of enthusiasts are finding that P965 overclocks a little further than 975X on average, a lot of power users would rather opt for a P965 motherboard instead of 975X, even though the 975X chipset was supposed to be tailored for the enthusiast. But then you lose the option of upgrading to CrossFire at some point in the future.
But what if there was a way you could add CrossFire support to the P965 chipset? Youíd have the best of both worlds, as youíd have the superior features and lower price of P965 and CrossFire support, a feature that up until now has been exclusive to 975X.
With their latest driver release, Catalyst 6.9, this is precisely what ATI has enabled for CrossFire enthusiasts who want a P965 motherboard. But to get it all up and running, there are a few caveats youíll have to keep in mind first. In this article weíre going to go over them, how well it all works, and finally, how it performs in comparison to 975X CrossFire. We also chat with ATIís new Director of Marketing for Platform Technologies (read: CrossFire) Godfrey Cheng, and take a look at a very early beta copy of ATIís upcoming Catalyst 6.10 driver which offers even more P965 CrossFire enhancements! Letís get startedÖ
In order to get CrossFire up and running on Intelís P965 chipset, ATI had to overcome two of the chipsetís chief limitations: lack of support for dual x8 PCI Express lane operation, and lack of support for peer-to-peer writes.
Ever since the first dual-GPU graphics solutions shipped roughly two years ago, both ATI and NVIDIA have been preaching about the importance of having both PCI Express graphics slots running synchronously with one another with an even number of PCI Express lanes Ė in the case of first generation SLI/CrossFire chipsets both PCI Express graphics slots ran in x8 mode, with 8 lanes devoted to each PCI Express graphics slot, more recent chipsets from ATI and NVIDIA have increased this amount to 16 lanes to each slot, providing more potential bandwidth and thus theoretically increasing performance. (Intelís 975X chipset runs both graphics slots in x8 mode for CrossFire.)
But the P965 chipset can only devote up to four lanes to the second PCI Express graphics slot for CrossFire. As a result, the primary graphics slot runs with all 16 lanes, while the second PCI Express graphics slot gets just four lanes. This is far from running both graphics slot in synch with each other.
The other limitation of Intelís P965 chipset is that it lacks support for peer-to-peer writes. In laymenís terms, this prevents the GPUís from sharing data properly with one another. For instance, if both graphics controllers need the same texture map, the render-to-texture data can be passed to both via peer-to-peer PCI Express.
How does ATI get around these limitations?
ATI hasnít been very specific about how theyíve gotten around the lack of PCI Express lanes on the secondary graphics slot for P965 CrossFire to operate, but we can provide more info on the second issue. In order to do this, itís important that we quickly explain the basics of how CrossFire works.
Because most of the hard work in terms of communications is done by the TMDS receiver present on the CrossFire master card, ATI has been able to get CrossFire up and running on P965 even though the chipset lacks support for peer-to-peer writes.
ATIís 6.9 driver release is the first Catalyst driver to offer support for P965 CrossFire, however Catalyst support in the 6.9 driver is limited to just Direct3D applications. ATI plans on adding support for OpenGL apps like Quake 4/Prey later this year.
ATIís driver team decided to focus on Direct3D rather than OpenGL first, as most games that are out on the market today utilize Microsoftís Direct3D API rather than OpenGL. So by supporting D3D first, they can provide P965 CrossFire support to a much wider selection of apps.
The second software component youíll need is a CrossFire compliant BIOS. Already ASUS, Gigabyte, and MSI have released CrossFire-compliant BIOSí for their P965 motherboards. ASUS in particular has been quite busy releasing new BIOS revisions. The latest BIOS available publicly on their website for the P5B Deluxe is their 0706 BIOS, which was released last week, but behind the scenes ASUSí engineers have developed quite a few revs since 0706.
We ran our tests with ASUSí 0710 BIOS, which adds support for ASUSí C.G.I. BIOS setting. C.G.I. stands for Cross Graphics Impeller and itís unique to ASUSí P5B Deluxe line. According to ASUS, C.G.I. ďstreamlines data transfer between the Northbridge and Southbridge, delivering enhanced performance during Crossfire dual-GPU mode.Ē
Since the four PCI Express lanes for the secondary PCI Express graphics slot hang off the P965 chipsetís South Bridge, enhancing data transfers between the P965ís North and South Bridge should enhance P965 CrossFire performance according to ASUS. This certainly sounds plausible in theory, so we figured weíd test out ASUSí C.G.I. BIOS setting, youíll see the results of those tests on the next few pages.
The future: more performance, more compatibility
ATI enthusiasts will be glad to hear that ATI isnít resting on their laurels, theyíre determined to continue to improve P965 CrossFire performance and compatibility, starting with the release of Catalyst 6.10 next month.
FiringSquad: With your upcoming merger with AMD expected to close at the end of this year, are you concerned that Intel may attempt to lockout the CrossFire platform on upcoming chipsets beyond todayís P965 and 975X?
Godfrey Cheng ATI: Pretty sneaky Brandon. Your question is really around open platforms. Certainly both ATI and AMD believe in open platforms and open competition and choice for the customer. Speaking for ATI, we want customers to pick the best CPU, GPU and Chipset Ė we welcome open competition. CrossFire has been an open platform from the beginning and it will continue to be an open platform even after our merger to AMD closes. CrossFire will continue to support Intel chipsets and Intel has given no indication that they will lock out ATI graphics in the future. Closed platforms, or platforms that tie GPUs and Chipsets together, are archaic and out-of-place in the modern PC. People should demand open platforms to give them greater choice.
FiringSquad: Youíve announced that the Radeon X1900 XT/XTX CrossFire is compatible with P965 CrossFire today with Catalyst 6.9 and that X1950 XTX CrossFire support is coming in Catalyst 6.10, but what about adding support for the Radeon X1800 XT CrossFire in a future release?
Godfrey Cheng ATI: Radeon X1800XT CrossFire works on the P965 platform today
FiringSquad: One of CrossFireís chief advantages over SLI is your Super AA performance scaling. Considering this, have you considered adding additional AA/AF modes to CrossFire for even better image quality?
Godfrey Cheng ATI: Yes one of many advantages that CrossFire has over SLI is our image quality. We plan on introducing a new AA mode shortly even for single card PCs. Stand by.
FiringSquad: Up to this point weíve basically been told that for best performance with dual-GPUs, itís best for both graphics slots to run with an even number of PCI Express lanes (either 8x8 or 16x16), and that if you donít thereís a slight performance penalty. So my question is, what tweaks are you planning to integrate into forthcoming Catalyst drivers to get around this?
Godfrey Cheng ATI: We maintain that a 16X16 or an 8X8 configuration is preferable to a 16X4 configuration. However, the hand that we were dealt with the P965 is 16X4 and we have really smart engineers who adapted our CrossFire architecture to support the P965ís 16X4 with minimal performance and compatibility impact.
FiringSquad: With the 975X and now P965 chipsets both supporting CrossFire, has this affected your plans for the RD600 chipset or are you still planning on going forward with this product? If yes, could you give us an ETA on when it will be available?
Godfrey Cheng ATI: As an open platform, in addition to supporting Intelís chipset, we will of course support our own. There will be RD600 based motherboards released to the public this year. We are confident that the RD600 chipset will be very competitive versus Intel chipsets from both a performance and price perspective.
FiringSquad: At Computex you demonstrated ATI physics up and running in a three-slot RD600 system running CrossFire. Can you give us an update on how physics is progressing and how it will be tied into CrossFire?
Godfrey Cheng ATI: We are still extremely enthusiastic when it comes to physics in games. As discussed at Computex, we are just a cog in the equation to getting physics-enabled games to the customer. We are working with many developers and other key companies to bring physics to the market. Physics will be an integral part of our Crossfire strategy.
FiringSquad: It has been widely speculated that your upcoming RV570 GPU will feature TSMCís 80-nm manufacturing process and more importantly, that youíre integrating the CrossFire compositing engine onto the GPU itself, so that all of these cards will support your CrossFire technology out-of-the-box without the need for a dedicated CrossFire master card SKU like youíve done for the X1800/X1900/X1950 GPUs. Will these cards be compatible with P965 CrossFire?
Godfrey Cheng ATI: Brandon, if I spill the beans now, we should just eliminate all product launches and reviews. The only comment that I will provide here is that we have actively listened to gamers and will continue to do so to make CrossFire their platform of choice.
FiringSquad: While CrossFire supports a number of games, there are still even more titles out there that donít have native CrossFire support. Considering this, have you thought about giving end users the option to force CrossFire rendering modes for specific games? One feature NVIDIA provides is SLI profiles, where you can tweak the SLI rendering mode depending on the game. Has ATI considered adding something similar to Catalyst Control Center for CrossFire?
Weíre testing with a mixture of both Catalyst 6.9 and Catalyst 6.10 so you can see the performance improvements ATI has integrated into their upcoming 6.10 driver. The 6.10 results will be highlighted in yellow to keep things simple.
Looking over our results with F.E.A.R., ASUSí C.G.I. setting definitely improved the Radeon X1900 XTXís CrossFire performance with the P965 chipset. Obviously weíre CPU-bound at 1280x1024, so youíll want to disregard those results, but at 1600x1200 and 1920x1200 we saw performance improvements of 2% and 3% respectively when using Catalyst 6.10, and 3% and 5% under Catalyst 6.9 at 1600x1200 and 1920x1200 respectively.
Performance is basically unchanged in Half-Life 2 Lost Coast. Our Radeon X1900 XTX CrossFire setup performs basically the same whether weíve got C.G.I. enabled or disabled.
Call of Duty 2
Performance in Call of Duty 2 is up slightly thanks to the ASUS C.G.I. feature. At 1280x1024 we saw a performance improvement of 5% once the setting was turned on when using Catalyst 6.10 and 4% for Catalyst 6.9, and while the margins narrow at higher resolutions, we still saw a nice boost of 2% for Cat 6.10 and 3% for Catalyst 6.9.
Oblivion: Mountains Area
Whether we tested outdoors in the mountains of Jarrell, or in our GPU-intensive foliage area performance was basically unchanged in Oblivion regardless of whether C.G.I was turned on or off.
Thanks to the improvements ATI has integrated into their Catalyst 6.10 driver, we saw no performance benefit from ASUS C.G.I. in 3DMark 06. However, under Catalyst 6.9 performance improved by about 3%.
Again, donít pay attention to the 1280x1024 results as weíre likely CPU or driver bound at that resolution with the Radeon X1900 XTX CrossFire configuration. At the other resolutions both P965 CrossFire and 975X CrossFire perform the same in F.E.A.R. regardless of driver used, so the 965 chipset is able to deliver equal performance to 975X despite its limitations.
Like F.E.A.R., Half-Life 2 Lost Coast CrossFire performance is equal between the P965 and 975X chipsets. It looks like ATIís driver team has already done a good job optimizing Lost Coast performance in Catalyst 6.9, performance is the same in 6.10 as well.
Call of Duty 2
Judging by our results, it looks like ATIís driver team may have found a slight performance increase for Call of Duty 2, at least at lower resolutions. At 1280x1024 the P965 CrossFire setup performance improved by 3%, 975X performance was only up slightly though.
Like F.E.A.R. and Half-Life 2 Lost Coast, it looks like ATIís driver team has got P965 CrossFire performance optimized pretty well in Oblivion, already the 965 chipset has pulled even with 975X with Catalyst 6.9.
ATIís P965 CrossFire performance improves substantially in 3DMark 06 under Catalyst 6.10, our 3DMark 06 score went from 9174 3DMarks to 10242 3DMarks, an improvement of 10.5%! As a result of these optimizations, P965 CrossFire should pull even with 975X once Catalyst 6.10 is released next month. Nice work ATI!
Unlike the X1900 XTX CrossFire results, the X1950 XTX P965 CrossFire setup isnít able to pull even with 975X CrossFire, with P965 CrossFire running up to 4% slower than 975X CrossFire. Considering the limitations of the P965 chipset though, only running 4% slower isnít that bad, in fact, at higher resolutions the margin separating the two chipsets decreases, at 1920x1200 thereís only a 1 fps difference in performance making it a draw.
Again, the Radeon X1950 XTX CrossFire setup runs a little bit slower on the P965 chipset, which differs from the results we saw with Radeon X1900 XTX. Performance is close between both platforms though, weíre only talking a 2% difference in performance, you likely wouldnít feel the difference between them when playing in-game.
Call of Duty 2
975X CrossFire enjoys a substantial performance advantage over P965 CrossFire, at 1280x1024 the difference between the two platforms is a whopping 27%. Even at 1920x1200 the 975X platform outran P965 by 18%, so it looks like thereís still quite a bit of room for performance tweaking in Call of Duty 2.
Oblivion: Mountains Area
975X CrossFire also enjoys a performance advantage in Oblivion, whether weíre testing in our foliage area or the mountains. The performance edge isnít too substantial though, itís roughly anywhere from 3-7% depending on the area tested and the screen resolution.
ATIís already got Half-Life 2 Lost Coast and F.E.A.R. running well with the Radeon X1900 XTX CrossFire. P965 CrossFire performance is on par with 975X CrossFire in both of those games based on our testing. RPG fans will be glad to see Oblivion running well with that config also.
Of the benchmarks we tested, Call of Duty 2 was the one app that definitely still needs work. In CoD 2, the 975X CrossFire platform ran up to 22% faster under Catalyst 6.9 at 1280x1024, and 20% faster with Catalyst 6.10 at the same resolution. Based on the results we saw in the other benchmarks though, we wouldnít be surprised if ATI is able to narrow this margin eventually with newer drivers. Keep in mind that all these results were taken with ASUSís C.G.I. setting enabled.
Like ATIís driver team, ASUS is determined to bring P965 CrossFire performance as close to 975X as possible. Theyíve been feverishly working on newer BIOS revisions for the P5B Deluxe family to improve its CrossFire performance in comparison to competing P965 motherboards from other manufacturers, their C.G.I. technology is one such example of this.
With C.G.I. ASUS has optimized data transfers between the Direct Media Interface (DMI) that links the P965 North Bridge to the South Bridge. This is important because the PCI Express lanes for the secondary graphics slot come from the chipsetís South Bridge. With communications between the two chips improved, overall 3D performance also improves. We saw performance improvements of anywhere from 2-5% once C.G.I. was enabled, with the result depending on the benchmark and screen resolution tested.
ATIís Radeon X1950 XTX doesnít appear to be faring quite as well however. The 975X CrossFire setup outperformed P965 CrossFire consistently, even in F.E.A.R. and Oblivion. P965 CrossFire ran about 3-7% slower in Oblivion for example. The X1950 XTX is much newer than the X1900 XTX though, so ATIís driver team hasnít had as much time to optimize for its new GDDR4 memory controller.
In the future ATI plans to include OpenGL P965 CrossFire support. That will open CrossFire up to games like Quake 4 and Prey. ATIís upcoming 6.10 driver brings with it official support for the Radeon X1950 XTX, and also other goodies like integrated support for HDR+AA in apps like Oblivion (this was previously provided under the separate Chuck patch driver).
975X CrossFire will always have one advantage though: hardware compatibility. Since the P965 chipset lacks support for peer-to-peer writes, dongle-less CrossFire solutions like the Radeon X1900 GT and Radeon X1800 GTO canít be paired together to run CrossFire on P965. If you have one of these graphics cards, youíll have to buy a 975X motherboard if you want to run CrossFire.
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