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AMD CrossFireX and Hybrid Graphics Performance Preview March 04, 2008 Brandon Sandman Bell |
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Summary: AMD's launching 2 new technologies with the debut of Catalyst 8.3: CrossFireX and Hybrid Graphics. In this article we're going to examine how 2, 3, and 4-Way CrossFire compares to NVIDIA's 2 and 3-Way SLI. We'll also take a look at Hybrid Graphics performance. Does the IGP+GPU combo really work? Find out in today's article!
 Introduction | Page:: ( 1 / 17 ) |
Back when the Radeon HD 3870 and 3850 were launched last year, AMD promised CrossFireX drivers before the end of Q1’08. Well folks, today is that day. AMD’s upcoming 8.3 Catalyst driver release (set to debut by Wednesday), not only supports CrossFireX, but also AMD’s Hybrid Graphics technology that’s designed to bring the world of CrossFire to integrated graphics platforms based on AMD’s RS780 chipset, which is also launching alongside Catalyst 8.3 today.
Today we’re going to take a look at two potential CrossFireX configurations, as well as Hybrid Graphics. We’ve only had the final 8.3 driver for a little over 72 hours, so unfortunately we haven’t had the time or resources to test more configs. Rest assured that we’ll take a look at them over the coming months.
So what is CrossFireX?
CrossFireX is AMD’s third generation CrossFire technology. AMD’s first attempt at CrossFire with the Radeon X800 family never really took off due to the limitations of the technology: cards were capped at a max resolution of 1600x1200 at 60Hz and the dedicated CrossFire master card with its own bulky interconnect cable really turned off enthusiasts. AMD’s second generation CrossFire tech debuted in the Radeon X1950 Pro and was warmly received thanks to its native CrossFire support that was built in to the GPU as well as featuring a new high-speed 24-bit connection.
The seeds for 3 and 4-way CrossFire were actually planted during this generation, with X1950 cards sporting dual CrossFire connectors. Unfortunately however, CrossFireX support is limited to AMD’s RV670 and R680 GPUs, so the implied suggestion that X1950 cards would one day support 4-Way CrossFire were unfortunately untrue.
In their defense though, AMD has made CrossFireX more flexible than previous multi-GPU solutions. One key feature that CrossFireX supports is the ability to mate any RV670 or R680-based graphics card with another. This means that you can combine two Radeon HD 3850s with a Radeon HD 3870, or a Radeon HD 3870 X2 with a 3850 for 3-Way CrossFire. Or you could pair two 3850s with two 3870s, or two 3870 X2 cards for 4-Way CrossFire. There are literally three dozen different combinations:
[image]
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CrossFireX is also supported by a variety of different platforms, not only are AMD’s own chipsets supported, but Intel chipsets are supported as well:
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As the first chat above indicates, in cases where cards with different memory sizes are combined together to run in CrossFireX mode, the card with the least amount of memory will become the limitation. So if three 512MB Radeon HD 3850 boards are paired with one 256MB card, all four boards will run as 256MB cards. The same applies to cards running at different clock speeds – all the cards will only run as fast as the slowest card.
Because of this, while all your cards don’t have to be identical to one another, or even utilize the same GPU, it is important that they’re not too out of sync with one another. i.e. you won’t want to mix a 256MB board with a pair of 512MB boards, or a 3850 card that doesn’t OC well with a factory overclocked 3870 or 3870 X2.
| CrossFireX Implementation | Page:: ( 2 / 17 ) |
While CrossFire had traditionally supported multiple rendering modes like split frame rendering (SFR), and supertiling, for CrossFireX, the focus (at least initially) is solely on alternate frame rendering (AFR). In addition, for right now CrossFireX support is limited to Direct3D applications, OpenGL support will eventually be added in a later driver. We should also mention that 3 and 4-Way CrossFireX support is limited to the Windows Vista OS only; Windows XP isn’t supported (keep in mind that support for NVIDIA’s 3-Way SLI is also exclusive to Vista).
As you can imagine, some games scale better than others with CrossFireX. Right now CrossFireX generally scales better in DX9 apps than DX10. Apparently new features first introduced in DX10 as well as greater usage of persistent resources made the new API more flexible than DX9 for developers, but are now causing headaches for the CrossFireX driver team. The following chart summarizes the scaling AMD’s own labs have seen (we’ll be putting this to the test shortly in our own benchmarks):
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As AMD’s driver team has more time to optimize and tweak their graphics driver, expect performance to improve. Also keep in mind when looking at our benchmarks that with up to four GPUs running in tandem, the CPU can become a bottleneck at 1600x1200 depending on the game being tested. In a game based on an older engine like Half-Life 2: Episode Two, we were CPU-bound at 1600x1200 and 1920x1200 in our testing.
Hybrid Graphics
Catalyst 8.3 also includes support for AMD’s Hybrid Graphics technology. Simply pair any AMD 780G (RS780/Radeon HD 3200) motherboard up to a Radeon HD 3450 graphics card for nearly double the performance. Then, when you’re done gaming, you can disable Hybrid Graphics via the control panel to conserve power, or if you’d like, you can connect up to four displays to the system. We’ve included a few Hybrid Graphics benchmarks at the end of this article.
Other improvements
Besides these new features, AMD has added other new features to Catalyst 8.3. Here’s what we’ve been told by AMD:
DirectX 10.1 and Tessellation Support:
ATI Catalyst 8.3 marks the first time DirectX 10.1 support for the ATI Radeon HD 3000 series, and tessellation support for the ATI Radeon HD 3800 series have been made available to developers.
Anti-Aliasing enhancements:
This release of ATI Catalyst introduces anti-aliasing support for all Unreal Engine 3.0 based games (running in DirectX 9 mode). Users can enable Anti-Aliasing for titles such as Gears of War and Unreal Tournament 3 by simply enabling Anti-Aliasing within the ATI Catalyst Control Center. This release of ATI Catalyst allows users to enable the Edge Detect Anti-Aliasing filters while running in the Crossfire Super Anti-Aliasing modes, providing an improved image quality experience.
ATI Catalyst Control Center: HydraVision support for Windows Vista:
This release of ATI Catalyst introduces HydraVision support for the ATI Catalyst Control Center under Windows Vista. HydraVision enables users to more efficiently organize multiple applications across single or multiple displays. High-lights include:
Digital Panel GPU image scaling:
This release of ATI Catalyst introduces a new setting that allows users to enable GPU accelerated scaling for LCD displays. The new setting “Maintain aspect ratio” improves the display resolution image quality when scaling is enable by maintaining the wide panel aspect ratio (stops the image from looking distorted) on wide aspect LCDs.
ATI Catalyst Control Center: Advanced Video Quality controls:
This release of ATI Catalyst introduces new advanced video quality controls: Edge enhancement, which adjusts the level of sharpness of video content, and noise reduction, which removes ghosting artifacts while preserving details of the original video. The new slider controls can be found in the All Settings page of the Avivo Video tab found in the Catalyst Control Center.
| System Setup | Page:: ( 3 / 17 ) |
Intel Core 2 Extreme X6800
AMD Athlon 64 X2 4850e
ASUS P5E3 Deluxe (for Radeon cards)
EVGA nForce 780i SLI motherboard (for GeForce cards)
Gigabyte MA78GM-S2H (for Hybrid Graphics platform)
4GB Corsair TWIN2X2048-6400C4
AMD Radeon HD 3870 512MB
AMD Radeon HD 3870 X2 1GB
ASUS EAH 3870X2 TOP 1GB
Catalyst 8.3
GeForce 8800 GTX 3-Way SLI
GeForce 8800 GTS SLI
ForceWare 169.28
300GB Western Digital Caviar SE
Windows Vista 64-bit w/Service Pack 1
Benchmarks
Company of Heroes 1.71
F.E.A.R. 1.08
Elder Scrolls IV: Oblivion
Half-Life 2 Episode Two
Lost Planet
Crysis 1.1
| F.E.A.R. Performance | Page:: ( 4 / 17 ) |
| Company Of Heroes DX9 | Page:: ( 5 / 17 ) |
| Oblivion | Page:: ( 6 / 17 ) |
| HL2 Episode 2 | Page:: ( 7 / 17 ) |
| Lost Planet DX10 | Page:: ( 8 / 17 ) |
| Crysis DX10 2xAA | Page:: ( 9 / 17 ) |
Crysis Very High – Direct3D
| Hybrid Performance: Lost Planet | Page:: ( 10 / 17 ) |
| CoH Hybrid Graphics Performance | Page:: ( 11 / 17 ) |
| Hybrid Graphics Performance w/Episode 2 | Page:: ( 12 / 17 ) |
| BioShock w/Hybrid Graphics | Page:: ( 13 / 17 ) |
| Crysis Hybrid Performance | Page:: ( 14 / 17 ) |
| Oblivion Hybrid Performance | Page:: ( 15 / 17 ) |
| FEAR | Page:: ( 16 / 17 ) |
| Conclusion | Page:: ( 17 / 17 ) |
In F.E.A.R., the 3-Way CrossFireX testbed outran the 3870 X2 by 24% at 1920x1200, while the 4-Way system was 7% faster than 3-Way. In this case adding that fourth card really didn’t buy us that much. 4-Way CrossFire is also overkill if you plan on running Episode Two at anything less than 2560x1600. In this game you’d probably want to crank up the AA to one of AMD’s SuperAA modes if you insist on using CrossFireX.
As AMD’s Catalyst team has more time to work on improving their drivers, expect CrossFireX performance to go up from here.
What really excites us the most about CrossFireX though is its scalability. Not only can you easily scale from two, to three, and finally four GPUs, you can also mix and match graphics cards. With dozens of different potential combinations, this gives end users lots of flexibility when it comes to upgrading. And since CrossFireX is supported by cards ranging in price from roughly $155 all the way up to $400+, the technology is attainable for gamers at multiple price points. In comparison, NVIDIA’s 3-Way SLI is a feature that’s exclusive to high-end $400+ graphics cards. We appreciate the fact that AMD is making the ultra high end within reach of gamers regardless of their budget. By doing so, it certainly creates more work for their driver team, as they have to tweak and test compatibility with a wider range of products.
The other really neat feature that we appreciate about CrossFireX is its platform support. Not only is it supported by all of AMD’s CrossFire chipsets (both past and present), but also Intel’s. Considering the arch rivalry that exists between the two companies, it’s surprising and refreshing to see them working together for the benefit of the end user. We wish NVIDIA’s SLI platform was as open an AMD’s CrossFire platform is.
On the integrated graphics front, AMD’s Hybrid Graphics is a groundbreaking feature. By combining the Radeon 3200 IGP with a $50 Radeon HD 3450 graphics card, we saw a dramatic performance improvement in some cases. At 1024x768 and 1280x1024 we saw a performance increase of ~2X in Lost Planet and Oblivion, while Company of Heroes performance improved by greater than 2X!! We also saw a performance improvement of 30% or more in Crysis, while BioShock’s performance improved by up to 25%.
Now granted these performance improvements didn’t allow us to crank up the AA to max or anything like that, but for a $50 upgrade these are very nice gains. Gamers on a budget will still want to pick up a nice mainstream card in the $120-$200 range, but for the average joe who just wants to see what all the fuss in Crysis is all about, he can get a taste of the game without having to shell out the cash for a decent midrange card. This is a move that can make PC gaming compelling for the people who spend less than $500 on a PC.
In their eyes, it makes no sense to spend $100+ or more on one component when they got their whole PC for less than $500. Of course, as gamers we all know by now that the GPU is the most important component in your PC when it comes to gaming performance, but these consumers don’t have a clue what a GPU is unfortunately. Hopefully system builders and AMD’s board partners will include marketing material that promotes Hybrid Graphics with their 780G products (much like NVIDIA has done with SLI), so that these consumers can get educated on how the technology works.
We’ll be taking a closer look at the 780G platform and how it compares to the competition from Intel in a standalone article. Already though the platform looks killer when it comes to graphics; this has been a sore spot for Intel for quite some time, and with the debut of 780G, the problem is only going to get worse for them…