P965 Gets CrossFire: 975X vs P965 CrossFire Performance w/ASUS P5B Deluxe & Catalyst 6.10 October 01, 2006

Introduction

Page:: ( 1 / 20 )

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 you’ve basically got two choices -- 975X or P965 (Intel has other Core 2-compatible chipsets as well, but for varying reasons these really aren’t ideal for enthusiasts)

If you cared about ATI’s CrossFire graphics technology, up to a few weeks ago the choice was pretty simple: Intel’s 975X chipset. 975X is Intel’s high-end enthusiast level chipset, and was the only chipset to support CrossFire out of the gate at Core 2’s launch. But 975X is an older chipset, and is limited to officially supporting just DDR2-667 memory. In comparison, Intel’s 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 BIOS’, but officially this is considered overclocking by Intel/motherboard manufacturers, so you’ll get no support if it doesn’t work.

[image]

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 you’ll have to keep in mind first. In this article we’re going to go over them, how well it all works, and finally, how it performs in comparison to 975X CrossFire. We also chat with ATI’s new Director of Marketing for Platform Technologies (read: CrossFire) Godfrey Cheng, and take a look at a very early beta copy of ATI’s upcoming Catalyst 6.10 driver which offers even more P965 CrossFire enhancements! Let’s get started…

P965 CrossFire

Page:: ( 2 / 20 )

In order to get CrossFire up and running on Intel’s P965 chipset, ATI had to overcome two of the chipset’s 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 – 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. (Intel’s 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 Intel’s P965 chipset is that it lacks support for peer-to-peer writes. In laymen’s terms, this prevents the GPU’s 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.

[image]

How does ATI get around these limitations?

ATI hasn’t been very specific about how they’ve 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, it’s important that we quickly explain the basics of how CrossFire works.

Currently ATI has two ways of providing CrossFire: there’s ATI’s hardware-based solution, which relies on ATI’s compositing engine that’s built into CrossFire master cards, and the dongle-less solution that doesn’t require a CrossFire Master card, relying solely on the PCI Express interface instead. Let’s go over ATI’s hardware-based solution first.

Since ATI’s Radeon GPUs don’t have a native way to communicate with one another, ATI has had to integrate a number of chips to handle the communication and compositing necessary for CrossFire to function. This collection of chips is known as the compositing engine and is found only on CrossFire “Master” graphics cards.

How it works is pretty clever, the CrossFire Master card has a TMDS receiver which is used to intercept and decode the DVI output of the slave graphics card. From there ATI uses a Xilinx Field Programmable Gate Array (FPGA) as the compositing engine. The compositing engine then takes the partial image from the “Slave” graphics card and combines it with the other half of the image from the CrossFire master card. Once the images are combined, the final result is then sent out to your monitor via a dual-link TMDS transmitter.

[image]

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.

For dongle-less CrossFire to work however, PCI Express’ peer-to-peer functionality is required for the two Radeon graphics cards to communicate with each other. Since the P965 chipset lacks support for peer-to-peer writes, this means that ATI can’t get dongle-less CrossFire to work with their Radeon X1900 GT and X1800 GTO graphics cards. If you want to CrossFire two of these boards together, you’ll have to get a motherboard that uses Intel’s 975X chipset, there’s just no way around this.

What you’ll need

Page:: ( 3 / 20 )

ATI’s 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.

ATI’s driver team decided to focus on Direct3D rather than OpenGL first, as most games that are out on the market today utilize Microsoft’s 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 you’ll need is a CrossFire compliant BIOS. Already ASUS, Gigabyte, and MSI have released CrossFire-compliant BIOS’ 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 ASUS’ engineers have developed quite a few revs since 0706.

[image]

The future: more performance, more compatibility

ATI enthusiasts will be glad to hear that ATI isn’t resting on their laurels, they’re determined to continue to improve P965 CrossFire performance and compatibility, starting with the release of Catalyst 6.10 next month.

Catalyst 6.10 will be the first official driver to include support for the Radeon X1950 XTX, which will also support P965 CrossFire. In addition to adding support for the X1950 XTX, ATI’s hoping to improve on P965 CrossFire’s performance bringing it that much closer to 975X, despite the fact that the secondary graphics slot is only running in x4 mode.

We were given the opportunity to test out a prerelease beta copy of Catalyst 6.10 and were pleasantly surprised to see that ATI’s driver team has indeed delivered enhanced P965 CrossFire performance in some titles, but more on that later. We were given the opportunity to ask a few questions about all this to Godfrey Cheng, ATI’s Director of Marketing for Platform Technologies. Let’s see what Godfrey has to say about all this cool stuff shall we?

Q&A with ATI on CrossFire

Page:: ( 4 / 20 )

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 today’s 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 – 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: You’ve 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 CrossFire’s 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 we’ve basically been told that for best performance with dual-GPUs, it’s best for both graphics slots to run with an even number of PCI Express lanes (either 8x8 or 16x16), and that if you don’t there’s 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 P965’s 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 Intel’s 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 TSMC’s 80-nm manufacturing process and more importantly, that you’re 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 you’ve 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 don’t 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?

Godfrey Cheng ATI: We have considered this feature along with many others. There are several things that we want to do for our customers which includes Vista support and the support of new GPUs that we have in the pipe. Game profiling is one of the priorities we’re working on. In the meantime, we encourage our customers to use the Catalyst AI Aggressive setting to force AFR on any game which will provide much of the benefits of game profiling.



On behalf of FiringSquad, we’d like to thank Godfrey for answering our questions about CrossFire, and look forward to ATI’s future CrossFire enhancements. We’d also like to thank ATI’s Korhan Erenben who’s responsible for Avivo and CrossFire marketing, for answering our questions on CrossFire earlier this week as well.

Now we want to see what kind of performance improvements, if any, ASUS’ C.G.I. feature brings.

System Setup

Page:: ( 5 / 20 )

System Setup

Intel Core 2 Extreme X6800

ASUS P5W DH Deluxe (975X)
ASUS P5B Deluxe WiFi-AP

2GB Corsair TWIN2X2048-6400C3

ATI Radeon X1900 XTX CrossFire
Catalyst 6.9


ATI Radeon X1900 XTX CrossFire
ATI Radeon X1950 XTX CrossFire
Catalyst 6.10 pre-release beta

Windows XP Professional with Service Pack 2

DirectX 9.0c

Western Digital Raptor 74GB

Benchmarks

3DMark06
F.E.A.R. 1.07
Call of Duty 2 1.3
Half-Life 2 Lost Coast
Oblivion

Notes

We’re 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.

The Radeon X1950 XTX results at the end were taken solely with Catalyst 6.10, and ASUS C.G.I. was enabled in BIOS for all CrossFire tests unless otherwise noted.

C.G.I. results with F.E.A.R.

Page:: ( 6 / 20 )

F.E.A.R.

Notes

Looking over our results with F.E.A.R., ASUS’ C.G.I. setting definitely improved the Radeon X1900 XTX’s CrossFire performance with the P965 chipset. Obviously we’re CPU-bound at 1280x1024, so you’ll 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.

C.G.I. results with HL2 Lost Coast

Page:: ( 7 / 20 )

Lost Coast

Notes

Performance is basically unchanged in Half-Life 2 Lost Coast. Our Radeon X1900 XTX CrossFire setup performs basically the same whether we’ve got C.G.I. enabled or disabled.

C.G.I. results with Call of Duty 2

Page:: ( 8 / 20 )

Call of Duty 2

Notes

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.

C.G.I. results with Oblivion

Page:: ( 9 / 20 )

Oblivion: Mountains Area

Notes

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.

C.G.I. results with 3DMark 06

Page:: ( 10 / 20 )

Futuremark 3DMark06

Notes

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%.

P965 CrossFire Performance: F.E.A.R.

Page:: ( 11 / 20 )

F.E.A.R.

Notes

Again, don’t pay attention to the 1280x1024 results as we’re 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.

P965 CrossFire Performance: Half-Life 2 Lost Coast

Page:: ( 12 / 20 )

Lost Coast

Notes

Like F.E.A.R., Half-Life 2 Lost Coast CrossFire performance is equal between the P965 and 975X chipsets. It looks like ATI’s 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.

P965 CrossFire Performance: Call of Duty 2

Page:: ( 13 / 20 )

Call of Duty 2

Notes

Judging by our results, it looks like ATI’s 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.

975X CrossFire still enjoys a edge in performance over P965 CrossFire. At 1280x1024 the margin separating P965 CrossFire and 975X CrossFire is 20% with Catalyst 6.10, and 13% at 1920x1200.

P965 CrossFire Performance: Oblivion

Page:: ( 14 / 20 )

Oblivion

Notes

Like F.E.A.R. and Half-Life 2 Lost Coast, it looks like ATI’s 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.

P965 CrossFire Performance: 3DMark06

Page:: ( 15 / 20 )

Futuremark 3DMark06

Notes

ATI’s 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!

Radeon X1950 XTX Performance: F.E.A.R.

Page:: ( 16 / 20 )

Notes

Unlike the X1900 XTX CrossFire results, the X1950 XTX P965 CrossFire setup isn’t 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 isn’t that bad, in fact, at higher resolutions the margin separating the two chipsets decreases, at 1920x1200 there’s only a 1 fps difference in performance making it a draw.

Radeon X1950 XTX Performance: Half-Life 2 Lost Coast

Page:: ( 17 / 20 )

Notes

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, we’re only talking a 2% difference in performance, you likely wouldn’t feel the difference between them when playing in-game.

Radeon X1950 XTX Performance: Call of Duty 2

Page:: ( 18 / 20 )

Call of Duty 2

Notes

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 there’s still quite a bit of room for performance tweaking in Call of Duty 2.

Radeon X1950 XTX Performance: Oblivion

Page:: ( 19 / 20 )

Oblivion: Mountains Area

Notes

975X CrossFire also enjoys a performance advantage in Oblivion, whether we’re testing in our foliage area or the mountains. The performance edge isn’t too substantial though, it’s roughly anywhere from 3-7% depending on the area tested and the screen resolution.

Conclusion

Page:: ( 20 / 20 )

ATI’s 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 wouldn’t be surprised if ATI is able to narrow this margin eventually with newer drivers. Keep in mind that all these results were taken with ASUS’s C.G.I. setting enabled.

Like ATI’s driver team, ASUS is determined to bring P965 CrossFire performance as close to 975X as possible. They’ve 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 chipset’s 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.

ATI’s Radeon X1950 XTX doesn’t 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 ATI’s driver team hasn’t 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. ATI’s 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 can’t be paired together to run CrossFire on P965. If you have one of these graphics cards, you’ll have to buy a 975X motherboard if you want to run CrossFire.

In any case, thanks to the efforts of ATI’s driver team, P965 CrossFire is here today even though the chipset wasn’t designed to support it. We’ve once again got to give kudos to Terry and the rest of the crew at the Catalyst driver team, for working hard on tackling this. Despite the limitations of the P965 chipset when it comes to CrossFire it appears they’ve put together quite a nice alternative for those of you who can’t afford to spend the premium on 975X.