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ATI Radeon X1800 XT CrossFire Performance Preview December 20, 2005 Brandon Sandman Bell |
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Summary: Fullfilling their commitment to deliver a CrossFire solution to X1800 owners before the end of the year, today ATI's announcing the widespread availability of their Radeon X1800 XT CrossFire Edition card. ATI's latest CrossFire solution has been redesigned to run at higher resolutions with blistering frame rates. In fact, ATI's 14x Super AA mode had the GeForce 7800 GTX 512MB eating dust! Read on for the full scoop!
 Introduction | Page:: ( 1 / 13 ) |
Unfortunately for ATI, CrossFire, like many of ATI’s products that were introduced in 2005, suffered from lengthy delays. ATI had initially hoped to have CrossFire ready in time for the annual CeBIT tradeshow in March, in fact the show floor was abuzz with rumors and sightings of ATI’s dual-graphics technology, but ultimately ATI wasn’t ready to announce anything until the Computex tradeshow three months later in Taiwan.
CrossFire made quite a splash at Computex, ATI was quick to promote the virtues of their dual-graphics technology, claiming their CrossFire solution was more flexible than NVIDIA SLI: not only could you mix and match board vendors with CrossFire, the graphics card’s BIOS didn’t matter either. ATI also stated that CrossFire motherboards didn’t require selector cards or jumpers, unlike the SLI motherboards at that time. CrossFire also boasted a special “Super AA” mode sporting 8x, 10x, 12x, and 14x AA modes, enabling AA levels never seen before on the PC. And of course, you can’t forget ATI’s claim that CrossFire was compatible with practically all games (although when questioned they were quick to admit that this claim applies to Super AA and not performance improvements directly).
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Unfortunately for ATI, while three months may not seem like a very long time, in the 3D graphics industry, those three months between CeBIT and Computex were critical. By the time ATI was ready to announce their CrossFire technology, NVIDIA was just weeks away from hard launching their next-generation GeForce 7800 GTX GPU. Another problem CrossFire faced was availability, while ATI had announced that the first CrossFire products would hit shelves sometime in July, ultimately CrossFire wasn’t ready for another 3+ months. With retail shelves brimming with NVIDIA’s next-gen GeForce 7 hardware, CrossFire was quickly forgotten. By the time first-generation CrossFire hardware finally did hit shelves, ATI’s Radeon X1K launch was right around the corner. In addition, first-gen CrossFire X850 boards were limited to a max resolution of 1600x1200 at 60Hz. This limitation was a huge oversight on ATI’s part, as CrossFire doesn’t really begin to shine until you crank up the screen resolution.
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Further adding insult to injury was the fact that by the time CrossFire was finally ready, most of CrossFire’s advantages over NVIDIA SLI had been nullified. NVIDIA took every one of ATI’s bullet points favoring CrossFire and addressed them in future driver releases. First NVIDIA introduced two new SLI AA modes in ForceWare 77.76, then NVIDIA added mixed card vendor support in ForceWare release 80. In addition, NVIDIA’s motherboard partners began shipping their second generation of nForce4 SLI motherboards, most of which didn’t require a selector card to enable SLI.
Just like that, all of CrossFire’s key selling points were suddenly gone, and CrossFire hardware cost considerably more than equivalent SLI hardware.
ATI needed an answer to the SLI juggernaut, and today it has finally arrived in the form of the Radeon X1800 CrossFire. Let’s see what improvements ATI has incorporated into their latest CrossFire solution.
| All-new hardware | Page:: ( 2 / 13 ) |
Since ATI’s Radeon boards 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. The compositing engine on the CrossFire card 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. With each card’s workload cut in half, performance is improved. In fact, in a best-case scenario, performance should nearly double.
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Enhanced compositing engine
For the Radeon X1800 CrossFire board, ATI has improved the compositing chip, replacing the old Xilinx Field Programmable Gate Array (FPGA) found in the original Radeon X850 CrossFire with a newer, more powerful Xilinx FPGA. ATI claims that this new chip is faster than its predecessor, and is also more programmable. In theory, the new compositing engine can be reprogrammed to deliver enhanced performance, compatibility, or functionality in the future.
In addition, the new FPGA has been designed to handle the blending used for CrossFire’s Super AA mode. According to ATI, with the compositing engine handling hardware blending, the huge performance hit normally associated with Super AA is largely mitigated. In fact, as you’ll see in our Super AA testing, you’ll see that thanks to this feature Super AA is nearly free in some cases. In laymen’s terms, this means that you can turn on Super AA and see practically no performance penalty.
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Addressing the 1600x1200 limitation
Without a doubt, one of the chief criticisms leveled at ATI’s Radeon X850 CrossFire board was its lack of support for mega high resolutions. Radeon X850 CrossFire boards were limited to just 1600x1200 at a headache-inducing refresh rate of 60Hz. Fortunately, ATI has integrated two dual-link TMDS transmitters for DVI into the Radeon X1800 XT, much to the delight of Apple 30” Cinema display users.
The move to dual-link transmitters also has huge ramifications for Radeon X1800 CrossFire. With a dual-link interlink, DVI bandwidth is doubled, providing resolutions of up to 2560x1600. Previous ATI Radeon offerings relied on single-link DVI transmitters.
Other than these changes, the rest of the technology found in ATI’s Radeon X1800 CrossFire card carries over unchanged. You’ve got the same rendering modes (scissor, supertiling, and alternate frame rendering) and the same Super AA modes. As a member of the X1800 family, the Radeon X1800 CrossFire supports ATI’s new transparency AA feature, as well as ATI’s Smoothvision HD anisotropic filtering.
| The hardware | Page:: ( 3 / 13 ) |
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Radeon X1800 CrossFire card
You’d be hard-pressed to spot any physical differences between ATI’s Radeon X1800 CrossFire card and a plain-jane Radeon X1800 XT 512MB. ATI has used the exact same board design, with the sole additions being the seven chips which comprise the compositing engine, and the VHDCI connection which lies alongside the card’s dual-link DVI connector (the Radeon X1800 CrossFire card also loses the S-Video connector present on X1800 cards). These chips lie just underneath the card’s fan. Power circuitry and cooling remain unchanged from the regular Radeon X1800 XT 512MB.
It’s the cooling in particular that you’re going to be most concerned about when running two X1800 cards in CrossFire mode. As you know by now, ATI outfits the Radeon X1800 XT 512MB with a massive dual-slot cooler. This means that the clearance between the X1800 CrossFire Master Card and its Radeon X1800 Slave card may be just a few millimeters. ATI’s own RD480 “Halibut” reference motherboard suffers from the same problem.
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Fortunately, due to the design of the X1800’s cooler, this shouldn’t be too much of a problem. You see, the card gets fresh air from the right side of the graphics card, rather than the top of the card (which is where most cards get their air from). The X1800’s blower-style fan sucks the air inside a ducted plastic enclosure, across the card’s massive copper heatsink, and ultimately the hot air is exhausted outside your system’s case. Therefore, even though the bottom X1800 card blocks the top X1800 card, the card on the top won’t overheat. We were able to run our Radeon X1800 CrossFire system for hours non-stop without any problems, despite the fact that the PCI-E graphics slots on our ASUS A8R-MVP CrossFire motherboard were barely separated. Of course, if you block the side of the card, that’s a totally different story.
The only exception to this rule is the Radeon X1800 XL, but more on this later.
The whole process isn’t quite as polished as NVIDIA’s SLI, but still, if you’re an experienced computer builder installing and setting up a CrossFire rig shouldn’t be too difficult. The most confusing aspect of the whole procedure is the wide variance between the CrossFire motherboards. Some CrossFire boards require a transposer card to sit in the unoccupied PCI-E graphics slot when running in single card mode, while others (DFI) don’t. The location of the primary PCI-E graphics slot also varies depending on the motherboard, on DFI’s CrossFire board the top PCI-E slot is the primary slot you’ll install the Radeon X1800 CrossFire board, whereas on both the ATI and ASUS boards the bottom PCI-E graphics slot is the primary slot. In the grand scheme of things, these are minor quibbles, but we do find it a little ironic that after bashing NVIDIA’s SLI selector card ATI’s own RD480 reference board requires a tranposer card of its own.
| Hardware (cont’d) | Page:: ( 4 / 13 ) |
Our ears in particular are quite thankful for this feature – every time you turn on your system, the fans on the Radeon X1800 operate at full tilt. At this speed, the combination of both fans on the Radeon X1800s can get quite loud (much louder than any graphics card ATI has produced to date), nearly rivaling NVIDIA’s infamous GeForce FX 5800 Ultra in noise levels. With the fans on two X1800 cards running at full speed, the noise generated inside your system is eerily reminiscent of a Jumbo Jet at takeoff. Since we run our testbed systems outside of a case, we could literally hear the whooshing sound of the air as it passed within the plastic duct of both X1800’s, while the card’s fan has a deep, menacing tone to it.
Thankfully this only lasts for the first few seconds when you initially boot up your system, once the OS loads the ATI graphics driver kicks in, immediately sending the fan to the card’s much quieter 2D mode. Even after extended gaming sessions with both cards under full load we never saw the cards fans crank up to their full speed, overall noise was noticeable but by no means terrible. By our guesstimate we’d rank it right between the GeForce 6800 GT SLI and 6800 Ultra SLI configurations we’ve tested in the past in terms of noise generated.
Compatibility
In terms of compatibility, all Radeon X1800 XT cards you purchase at retail should be compatible with the Radeon X1800 XT CrossFire card, regardless of manufacturer. In fact, we ran many of our tests with MSI’s Radeon X1800 XT 512MB as the slave card. OVERDRIVE support is provided as well.
You can also mix and match board configurations. Say for instance, running a Radeon X1800 XT 256MB with the 512MB Radeon X1800 XT CrossFire master board. Unfortunately, you’ll lose half of the CrossFire board’s memory though. Likewise, the Radeon X1800 XL is compatible with the Radeon X1800 XT CrossFire. In fact, if you’re currently an X1800 XL user, this is the only way you’ll get CrossFire support, as ATI has no plans to produce a CrossFire board for the X1800 XL.
That’s right, ATI Radeon X1800 XL users interested in CrossFire must purchase the X1800 XT CrossFire board, which carries an MSRP of $600 – roughly $200 more than the X1800 XL card you just bought. Fortunately, the X1800 XT CrossFire board will maintain its higher clock speeds, but you will lose half of the board’s memory. Here are a few tidbits from ATI’s official CrossFire FAQ on the matter:
What happens if you pair a 16-pipeline CrossFire™ Edition
graphics card with a CrossFire™ Ready 12-pipeline graphics
card?
In this scenario both graphics cards will operate as 12-pipeline
graphics cards while in CrossFire™ mode.
What happens if the CrossFire™ Edition graphics card and the
CrossFire™ Ready graphics card have different clock speeds?
Both cards will continue to operate at their individual clock speeds;
neither card is “stepped down.” The compositing engine on the
CrossFire™ Edition card merges the resulting images independent of
the clock speed on either graphics card.
This decision has interesting ramifications for the Radeon X1800 XL in particular, as not only do you have to fork over the extra dough for an X1800 XT CrossFire only to have your 512MB CrossFire board suddenly run as a 256MB card, you’ve also got to worry about cooling if you happen to have a CrossFire motherboard that doesn’t leave extra space between the PCI-E graphics slots and places the PCI-E primary graphics slot on the bottom of the motherboard.
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Motherboards we’ve tested that are affected by this include the ASUS A8R-MVP and ATI’s RD480 reference motherboard. Since the X1800 XL gets its fresh air from the top of the card rather than the side (as you see on the Radeon X1800), in these situations the X1800 CrossFire master board obstructs the X1800 XL’s air supply and consequently, the card’s fan has to crank up to higher RPMs to compensate. As a result, our CrossFire X1800 XL setup ran louder than the X1800 XT CrossFire system, and under extended gaming sessions, we did note numerous artifacts on the screen, particularly in Quake 4 for some reason. When this would occur, we’d have to turn off the system and wait for the X1800 XL card to cool down before booting the system back up.
Considering all this, we can’t recommend CrossFire as it’s implemented today for Radeon X1800 XL users. We quizzed ATI if they’d consider adding CrossFire support via the PCI-E graphics slot (similar to what they’re doing today for X1300 and X1600 users), but we’ve yet to hear back from them. Since both PCI-E graphics slots run in x8 mode once CrossFire is enabled, this potential solution is far from ideal, but in some ways its better than the alternative. ATI’s upcoming second-generation RD580 CrossFire motherboards will provide full 16-lane PCI-E support, even when running in CrossFire mode (just like NVIDIA’s nForce4 SLI X16 chipset), but these motherboards won’t debut until next year. Perhaps at that time, it may not be a bad idea for ATI to consider providing CrossFire support via PCI-E, as right now they’re pretty adamant that they won’t be producing a dedicated CrossFire master card for the Radeon X1800 XL.
Finally, we should note that ATI hasn’t been very specific in regards to Radeon X1800 XT CrossFire’s power requirements. We used our trusty OCZ ModStream 520W PSU and didn’t run into any problems.
| Test Systems | Page:: ( 5 / 13 ) |
System Setup
AMD Athlon 64 FX-57
ASUS A8N32-SLI Deluxe (for NVIDIA cards)
ASUS A8R-MVP (for ATI cards)
2GB OCZ DDR400 SDRAM
ATI Radeon X1800 XL 256MB
ATI Radeon X1800 XT 512MB
ATI Radeon X1800 XT CrossFire Edition 512MB
CATALYST 5.12
NVIDIA GeForce 7800 GTX 512MB
NVIDIA GeForce 7800 GTX
NVIDIA GeForce 7800 GT
Driver version ForceWare 81.95
250GB Maxtor Hard Drive Maxline III SATA Hard Drive w/16MB Cache
Windows XP Professional SP1
DirectX 9.0c
Benchmarks
IL-2 Sturmovik: Forgotten Battles
Half-Life 2
F.E.A.R.
Battlefield 2
Quake 4
Notes
We had to omit Call of Duty 2 for this round of tests. For some weird reason our NVIDIA-based system would lock up when loading levels if we ran the game’s DX9 rendering path; once we forced DX7 levels loaded regularly. We’ve run this combination of hardware/software in the past with no problems, so we’ll just chalk this one up to bad luck…
| Half-Life 2 4xAA/16xAF | Page:: ( 6 / 13 ) |
Half-Life 2 – Direct3D
| Battlefield 2 | Page:: ( 7 / 13 ) |
Battlefield 2 – Direct3D
| Quake 4 | Page:: ( 8 / 13 ) |
Quake 4 – OpenGL
| IL-2 4xAA/16xAF | Page:: ( 9 / 13 ) |
IL-2: FB – OpenGL
| F.E.A.R. Performance | Page:: ( 10 / 13 ) |
F.E.A.R. – Direct3D
Notes
Due to a bug in the CATALYST drivers, the X1800 cards don’t begin to really shine in F.E.A.R. until CATALYST A.I. is disabled (we’ve been doing this in all our recent graphics card reviews). In CrossFire mode however, we noted slightly stronger performance once CATALYST A.I. was turned back on. Based on how disappointing our dual-card CrossFire results are though, we have a sneaky suspicion that the driver is holding us back. Hopefully ATI will get all this sorted out in a future driver release.
| Super AA Performance: Quake 4 | Page:: ( 11 / 13 ) |
Quake 4 – OpenGL
Notes
ATI’s 8x Super AA mode hardly comes with a significantly reduced performance hit in comparison to GeForce 7800 GTX 512MB’s SLI Anti-Aliasing mode. In fact, ATI’s 14x Super AA mode often delivers performance comparable to, if not better than the GeForce 7800 GTX 512MB running 8x SLI Anti-Aliasing!
Unfortunately we couldn’t complete our Super AA tests with the Radeon X1800 XL CrossFire system without seeing artifacts, so we’ve omitted that setup from testing in Quake 4. We were able to run Half-Life 2 though…
| Super AA Performance: Half-Life 2 | Page:: ( 12 / 13 ) |
Half-Life 2 – Direct3D
| Final thoughts | Page:: ( 13 / 13 ) |
Speaking of the GeForce 7800 GTX 512MB, today’s stratospheric pricing on 512MB boards plays in CrossFire’s favor. If Radeon X1800 XT CrossFire boards are available at or near MSRP, you could pickup a Radeon X1800 XT CrossFire card for about $150 less than the GeForce 7800 GTX 512MB. The savings magnify when you factor in the cost of SLI versus CrossFire with a Radeon X1800 XT CrossFire setup costing roughly $1200, while a GeForce 7800 GTX 512MB will run you about $1500. Of course, considering ATI’s track record when it comes to availability, the million-dollar question everyone wants to know is how much will Radeon X1800 CrossFire ultimately cards sell for at retail? If supply is low and demand is high, history has shown that e-tailers will quickly markup the product, a $650 or $700 pricetag isn’t unreasonable. After all this is currently what’s happening to the GeForce 7800 GTX 512MB, as street prices on boards start about $100 over NVIDIA’s $650 MSRP for the GeForce 7800 GTX 512MB.
ATI says the first X1800 XT CrossFire boards will begin hitting shelves today, but again, ATI’s recent track record with announcing products well before they’re available at retail could occur again here. If Radeon X1800 XT CrossFire does hit retail on time and prices on retail boards are at or near MSRP however, ATI’s CrossFire solution could gain some traction.
Before you lucky folks with $1,000+ to spend get excited and start spec’ing out a CrossFire system though there are some quibbles that we must warn you about. For starters, there are the motherboards. Right now there are really only two CrossFire motherboards on the market, ASUS’ A8R-MVP and DFI’s Lanparty UT RDX200, both of which we have in-house here. Each board has their drawbacks, the DFI board is more enthusiast-oriented, with a wealth of BIOS options and extra space between the PCI-E graphics slots, but it also runs louder and is priced significantly higher than the ASUS board. On the other hand, the BIOS found in the ASUS board may disappoint some enthusiasts, while we would have liked a little more space between the PCI-E graphics slots (even though our Radeon X1800 XT CrossFire configuration ran perfectly). The DFI board has more features too.
In comparison, on the NVIDIA side you’ve got a ton of motherboard options to choose from, and at price points ranging from right around $100, all the way up to $200. It’s a much more mature infrastructure too.
The other downside to CrossFire is the implementation itself. As we stated earlier, it just isn’t as elegant as NVIDIA’s SLI solution. You’ve got to deal with thick dongles and you must always double-check to make sure CrossFire is turned on (ATI’s own reviewer’s guide mentions this), while the technology itself is really only useful to one card – the Radeon X1800 XT 512MB. Radeon X1800 XL support is provided, but when you consider that half the memory on the X1800 XT CrossFire must be disabled in order for everything to work, the bulk of the extra money you’re forced to fork over for a Radeon X1800 XT CrossFire card is essentially meaningless. In addition, a GeForce 7800 GT SLI setup performs similarly (outside of Super AA mode of course) but would cost hundreds of dollars less: two GeForce 7800 GT boards in SLI equal the cost of one Radeon X1800 XT CrossFire card!
Considering all this, while we’re much more enthusiastic about CrossFire today than we were three months ago with the X850 CrossFire board, we still wouldn’t classify the platform in general as being “better” than NVIDIA SLI, just different. If Super AA is your thing and you can’t wait to experience mega-AA modes then by all means, we’d definitely recommend ATI’s Radeon X1800 XT CrossFire solution, but for everyone else the maturity of NVIDIA’s SLI platform has inherent advantages that are pretty hard to beat, not to mention that SLI is more flexible, supporting every NVIDIA GPU on the market today rather than just NVIDIA’s flagship product. Given a little more time, we have no doubt that CrossFire can catch up to SLI, but it won’t happen with today’s CrossFire solution.
2005 will ultimately go down into 3D graphics history as the year dual-graphics solutions from ATI and NVIDIA became feasible. In the future, the technology is only going to get better and more powerful. Could you imagine running a quad-graphics configuration, or perhaps SLI and CrossFire will move into other areas such as physics or video playback? We’ll just have to wait and see…