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ATI’s Radeon X1800 CrossFire Edition graphics card

Scott Wasson Former Editor-in-Chief Author expertise
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ATI‘S FORTUNES HAVE BEEN dented a little bit by delays to its CrossFire dual-graphics solution and its Radeon X1000-series graphics chips, but red team has been scrambling to catch up. The company has brought to market most of the pieces of a brand-new, top-to-bottom lineup of products with a rapid-fire succession of product launches. After a few sputters, most Radeon X1000 series graphics cards are now available, as are CrossFire motherboards and video cards. ATI still needs to deliver a few missing pieces in order to catch up with its rival NVIDIA, and that’s what we have gathered here today.

If you’re longing to see a $1200 Radeon graphics subsystem under the Christmas three this year, you will need a Radeon X1800 CrossFire Edition graphics card. This magical device will allow you to sync up with a regular Radeon X1800 XT or XL graphics card for nearly double the rendering power of a single card. This new CrossFire card also sweeps away some of the limitations of the first-generation CrossFire hardware introduced just a couple of months ago, allowing mega-high-res gaming, among other things.

Now, we know the Radeon X1800 XT isn’t quite as bone-jarringly fast as NVIDIA’s new GeForce 7800 GTX 512, but it’s still a fire-breathing monster. Running two X1800 XTs together in CrossFire is a good way to strain your neck, singe your hair, or at least develop a very serious addiction to F.E.A.R.—but we’re willing to take that chance for you, our loyal readers. Keep reading to see how ATI puts on a Christmas light show, Radeon style.

Welcome your new master… card
Let’s start at the beginning and say that if all of this talk about “CrossFire” leaves you confounded, you probably ought to go read our initial review of ATI’s CrossFire solution. CrossFire involves a motherboard, a special video card, a regular Radeon, an external dongle cable connecting the two cards, and a graphics driver to animate all of this hardware. If you’re not familiar with this CrossFire contraption, you probably won’t understand the significance of a new CrossFire Edition card.

Our ATI Radeon X1800 CrossFire test rig

The Radeon X1800 CrossFire Edition

The card itself is very much like the Radeon X1800 XT that we reviewed not too long ago. It looks pretty much the same, and it packs a 625MHz R520 GPU and 512MB of GDDR3 memory, just like the X1800 XT. Oddly, though, our Radeon X1800 CrossFire review unit came with memory running at 720MHz, or 1440MHz effectively through the clock-doubling powers of DDR memory. The regular Radeon X1800 XT runs its RAM at 750MHz, or effectively 1.5GHz.

The minor discrepancy here is a little baffling, although it should have a fairly minimal impact on performance. When paired up with the Radeon X1800 XT, the CrossFire card should run its RAM at the lower speed while the XT maintains the higher RAM clock. CrossFire configs can run in these somewhat asymmetrical conditions with different GPU and memory clocks, although overall performance is usually gated by the slower of the two cards. Rendering every other frame (or a portion of each frame) on a slower graphics card tends to hold the faster card back.

Speaking of which, the Radeon X1800 CrossFire Edition can also work in concert with the Radeon X1800 XL, a lower end card with 500MHz GPU clock and only 256MB of memory clocked at 500MHz (or 1GHz effective). In fact, ATI has no plans to release a slower, less expensive CrossFire card to match up more exactly with the Radeon X1800 XL. If you want to do the dually thing with your X1800 XL, you’re gonna have to pony up for the full, six-hundred-dollar Radeon X1800 CrossFire experience. Then, once you plop the CrossFire card into your system next to the Radeon X1800 XL, the CrossFire card will proceed to deactivate half of its 512MB memory in order to match up with the XL’s RAM size. (The Radeon X1800 CrossFire will maintain its higher GPU and memory clock speeds, though.)

Transitioning in and out of CrossFire mode will be a little more inconvenient, too, since the system must be rebooted in order for the CrossFire card to deactivate half of its RAM. A chicken must also be sacrificed during the reboot. No reboot or ritual offering is required with the Radeon X1800 XT.

Building a better CrossFire
CrossFire configs with Radeon X1800 cards retain many of the same limitations that Radeon X800 and X850 versions have, including the need for a specialized “master” or CrossFire Edition card, an external dongle or Y-cable, and driver-based game profiles in order to improve performance. Radeon X1800 CrossFire still defaults to SuperTiling mode for load balancing if no application-specific profile specifying a different mode is available in ATI’s drivers, and based on our experience so far, SuperTiling remains a net performance loss versus a single card more often than not.

The X1800 version, though, isn’t limited to 1600×1200 resolution at 60Hz. It can run at up to 2560×1600 thanks to a more powerful compositing engine and the use of a dual-link DVI connection from the slave card to the master. (Err, card A to card B, if you’re intent on being politically correct.)

A bevy o’ chips on the X1800 CrossFire card

Even the new Radeon X1000 series GPUs weren’t designed with CrossFire capabilities expressly built in, so the “master” cards need some additional chips in order to handle the image compositing work for multi-GPU bliss. The Radeon X1800 CrossFire card really packs ’em in, too, with a total of at least seven different chips onboard to help.

The large chip on the left in the picture above is the heart of the CrossFire engine, a Xilinx Spartan XC3S400 FPGA, or programmable logic chip, that has been programmed to do the image compositing for CrossFire. This is a more powerful FPGA than the one on the Radeon X850 master card. ATI has taught the FPGA a new trick, too: how to do the blending required for CrossFire’s Super Antialiasing mode. Doing the blend in hardware here should alleviate some of the performance penalty associated with Super AA. ATI claims this new compositing engine is more flexible than the old one and could be reprogrammed to do new and different things via a flash ROM update, although they don’t seem to have any specific new capabilities in mind for it just yet. The flash ROM itself is the small chip just above the FPGA in the photo.

The two relatively large chips in the top right of the picture are Silicon Image SiI 163B TMDS receivers. These chips receive data from the slave card via the dual DVI links passed through the CrossFire dongle. Those links run at 165MHz, and each link can pass an image of up to 1600×1200 resolution at 60Hz. Combined, they give the Radeon X1800 CrossFire Edition the ability to pass through resolutions as high as 2560×1600. The two smaller Silicon Image chips are matching TDMS transmitters, used to drive any displays connected to the master card via the CrossFire dongle’s dual-link DVI output.

To the left of the TMDS transmitters is the same Analog Devices RAMDAC chip used on the Radeon X850 CrossFire. This little guy converts digital frame buffer info into an analog video signal suitable for CRT displays.

Obviously, adding all of this logic to the CrossFire card isn’t the ideal way to do things, and indeed, FPGA chips are often used to prototype logic that is later converted into a custom ASIC. I wouldn’t be shocked to see ATI incorporate CrossFire compositing logic directly into future GPUs, as NVIDIA has done with SLI.

The CrossFire connector is now a funky bifurcated job

ATI’s Master plan
ATI says Radeon X1800 CrossFire Edition cards will be available today at online retailers. Given ATI’s recent track record on that front, I’d say we can expect the cards to be generally available before Christmas, but I wouldn’t bet the bank on immediate gratification. These cards will ship at a princely list price of $599, and ATI expects to see the things actually selling at that price—or close to it. Hopefully, prices won’t rocket into the stratosphere the way those of the GeForce 7800 GTX 512 have, but that will depend on ATI’s supply and the markets demands, I suppose.

As for Radeon X1600 CrossFire cards, well, there’s been an apparent change in plans. ATI initially said it would be providing a CrossFire Edition of the Radeon X1600, but the new plan is to begin by offering “connectorless” CrossFire for this card. Simply plug a pair of these into the system and go—no master card or connector dongle is needed. The X1600 cards will have to pass data to one another via PCI Express, and doing so could hamper frame rates. However, rumor has it that ATI is planning to introduce a new chipset with dual 16-lane PCI Express slots, much like NVIDIA’s nForce SLI X16. This chipset might provide enough PCI Express bandwidth to sustain solid CrossFire performance for a pair of Radeon X1600s. ATI may yet decide to produce an X1600 CrossFire Edition master card, too, but I would be surprised to see it happen.

Our testing methods
As ever, we did our best to deliver clean benchmark numbers. Tests were run at least three times, and the results were averaged.

Our test systems were configured like so:

Processor Athlon 64 X2 4800+ 2.4GHz
System bus 1GHz HyperTransport
Motherboard Asus A8N-SLI Deluxe ATI RD480 CrossFire reference board
BIOS revision 1014 080012
North bridge nForce4 SLI Radeon Xpress 200P CrossFire Edition
South bridge RS450
Chipset drivers SMBus driver 4.50 SMBus driver 5.10.1000.5
Memory size 2GB (2 DIMMs) 2GB (2 DIMMs)
Memory type Crucial PC3200 DDR SDRAM at 400MHz Crucial PC3200 DDR SDRAM at 400MHz
CAS latency (CL) 2.5 2.5
RAS to CAS delay (tRCD) 3 3
RAS precharge (tRP) 3 3
Cycle time (tRAS) 8 8
Hard drive Maxtor DiamondMax 10 250GB SATA 150 Maxtor DiamondMax 10 250GB SATA 150
Audio Integrated nForce4/ALC850 with Realtek drivers Radeon X1800 CrossFire + Radeon X1800 XL 256MB PCI-E
with Catalyst 8-201-051122a-028804E drivers
Graphics GeForce 6800 GS 256MB PCI-E with ForceWare 81.87 drivers
Dual GeForce 6800 GS 256MB PCI-E with ForceWare 81.87 drivers Radeon X1800 CrossFire + Radeon X1800 XT 512MB PCI-E
with Catalyst 8-201-051122a-028804E drivers
XFX GeForce 7800 GT 256MB PCI-E with ForceWare 81.87 drivers
Dual XFX GeForce 7800 GT 256MB PCI-E with ForceWare 81.87 drivers
MSI GeForce 7800 GTX 256MB PCI-E with ForceWare 81.87 drivers
Dual MSI GeForce 7800 GTX 256MB PCI-E with ForceWare 81.87 drivers
GeForce 7800 GTX 512 512MB PCI-E with ForceWare 81.89 drivers
Dual GeForce 7800 GTX 512 512MB PCI-E with ForceWare 81.89 drivers
Radeon X1600 XT 256MB PCI-E with Catalyst 5.10a beta drivers
Radeon 800 XL 256MB PCI-E with Catalyst 5.10a beta drivers
Radeon X1800 XL 256MB PCI-E with Catalyst 5.10a beta drivers
Radeon X1800 XT 512MB PCI-E with Catalyst 5.10a beta drivers
OS Windows XP Professional (32-bit)
OS updates Service Pack 2, DirectX 9.0c SDK update (October 2005)

Thanks to Crucial for providing us with memory for our testing. 2GB of RAM seems to be the new standard for most folks, and Crucial hooked us up with some of its 1GB DIMMs for testing. Although these particular modules are rated for CAS 3 at 400MHz, they ran perfectly for us at 2.5-3-3-8 with 2.85V.

All of our test systems were powered by OCZ PowerStream 520W power supply units. The PowerStream was one of our Editor’s Choice winners in our last PSU round-up.

Unless otherwise specified, the image quality settings for both ATI and NVIDIA graphics cards were left at the control panel defaults.

The test systems’ Windows desktops were set at 1280×1024 in 32-bit color at an 85Hz screen refresh rate. Vertical refresh sync (vsync) was disabled for all tests.

We used the following versions of our test applications:

The tests and methods we employ are generally publicly available and reproducible. If you have questions about our methods, hit our forums to talk with us about them.

Doom 3
We generally used in-game controls when possible in order to invoke antialiasing and anisotropic filtering. In the case of Doom 3, we used the game’s “High Quality” mode in combination with 4X AA.

ATI’s recent driver optimizations for OpenGL are enough to vault the single Radeon X1800 XT ahead of the GeForce 7800 GTX 256MB, but the Radeon X1800 XT in CrossFire can’t quite sustain that lead. The Radeon X1800 XL-based CrossFire rig can’t catch the dual GeForce 7800 GTs, either. Still, the Radeon X1800 XT CrossFire system cranks out over 85 frames per second at 2048×1536. Like I said, it’s a monster. Unfortunately for ATI, the GeForce 7800 GTX 512 is practically otherworldly.

Half-Life 2: Lost Coast
This new expansion level for Half-Life 2 takes advantage of high-dynamic-range lighting, and it looks spectacular. HDR lighting requires the use of higher-color texture formats, so it really stresses a card’s throughput.

The Radeon X1800 CrossFire systems manage to outdo their closest NVIDIA counterparts at low resolutions here, but things change as the resolution steps up. Nevertheless, CrossFire scales nicely from one card to two.

Serious Sam II
Here’s a new game with a new game engine that takes advantage of all of the hottest lighting and shading techniques. Unfortunately, we decided not to test with high-dynamic-range lighting on this game because it didn’t appear to work correctly on Radeon X1000-series cards. Perhaps a future patch or driver update will resolve the problem.

Yow. The Radeon X1800 XL CrossFire setup beats out the GeForce 7800 GT SLI system in Serious Sam 2, at least at higher resolutions, and the X1800 XT CrossFire nearly catches the GTX 512.

We tested the next few games using FRAPS and playing through a portion of the game manually. For these games, we played through five 60-second gaming sessions per config and captured average and low frame rates for each. The average frames per second number is the mean of the average frame rates from all five sessions. We also chose to report the median of the low frame rates from all five sessions, in order to rule out outliers. We found that these methods gave us reasonably consistent results.

Light detail, shadow detail, texture resolution, shaders, effects detail, model decals, and reflections were all set to maximum for our testing. Computer performance, water resolution, and volumetric light density were set to medium.

The Radeon X1800 XT CrossFire system takes the top spot in our F.E.A.R. test when antialiasing is disabled, but it drops back a couple of spots in the field once 4X AA and 16X anisotropic filtering are enabled. The Radeon X1800 XL CrossFire rig can’t quite match the GeForce 7800 GT SLI system.

Battlefield 2

The fastest SLI and CrossFire systems bunch up at the top of the field here, likely due to a frame rate cap of 90Hz built into BF2. Any of these setups can run BF2 about as optimally as it can be run at 1600×1200 with 4X antialiasing. The Radeon X1800 XL CrossFire system is in league with the GeForce 6800 GS SLI setup—based on a much cheaper class of card.

Guild Wars

We found the same thing with the Radeon X1800 CrossFire systems that we did with Radeon X850 XT CrossFire. The game apparently has no profile in ATI’s drivers and defaults to SuperTiling mode, which actually produces lower frame rates than one would get from a single card. You’ll want to disable CrossFire altogether when playing games that trigger this sort of behavior.


3DMark05 bears out most of what we’ve seen already. The Radeon X1800 XT CrossFire system is typically faster than a pair of GeForce 7800 GTX 256MB cards in SLI but slower than dual 7800 GTX 512s. The X1800 XL in CrossFire, meanwhile, tends to trail the GeForce 7800 GTs in SLI.

The X1800 CrossFire systems fare relatively poorly in the first game test, particularly at 2048×1536.

3DMark05 (continued)

The CrossFire systems perform relatively stronger in the second and third game tests than they do in the first. The Radeon X1800 systems handle the Firefly Forest scene, which is full of complex geometry and shadows, especially well.

3DMark05 (continued)

These tests are a decent quick gauge of pixel-pushing power, and you can see that the Radeon X1800 XT is simply no match for the GeForce 7800 GTX 512. That’s doubly true in multi-GPU configs.

ATI’s cards tackle the complex vertex shader test with relish, but they trail a bit in the simple vertex test and in 3DMark’s relatively simplistic pixel shader bench.

SuperAA performance scaling
We haven’t had enough time with the Radeon X1800 CrossFire Edition to run a full spectrum of benchmarks with CrossFire’s Super AA modes, but here is a quick look at its performance in Doom 3. Also present is a test system based on the Asus A8N32-SLI motherboard with the nForce4 SLI X16 chipset. This chipset’s true dual 16-lane PCI Express slots have the potential to help NVIDIA’s SLI AA work a bit quicker.

ATI wasn’t kidding when they said hardware blending on the new CrossFire master cards would help with Super AA performance. The NVIDIA setups suffer a severe performance penalty for enabling SLI AA, while the Radeon X1800 CrossFire’s drop-off is proportionally much lower.

Well, I tried to overclock the CrossFire systems using the automatic clock config utility in the Overdrive section of ATI’s Catalyst Control Center. The app indicated a higher clock speed for at least one of the two cards (speeds aren’t displayed independently for both), but, well, here’s what I got for performance. Note that I’ve only labeled the overclocked Radeon X1800 XL CrossFire system as “OC.” I know that the CrossFire Edition card was running its memory at a higher clock speed, but I have no idea about the Radeon X1800 XL.

We’ll have to try this again with a future driver or a third-party tool that’s more capable. Surely we could squeeze more performance out of an overclocked CrossFire rig.

Power consumption
We measured total system power consumption at the wall socket using a watt meter. The monitor was plugged into a separate outlet, so its power draw was not part of our measurement. The idle measurements were taken at the Windows desktop, and cards were tested under load running Half-Life 2: Lost Coast at 1600×1200 resolution with 16X anisotropic filtering and HDR lighting enabled.

All of the graphics cards named below except for the two Radeon X1800 CrossFire setups were tested on the Asus A8N-SLI mobo. We were forced to use the ATI CrossFire reference mobo, of course, for the CrossFire cards. Thus, the numbers below are an indication of overall platform power consumption, but they encompass more variables than just the graphics cards’ power use alone.

High-end multi-GPU systems aren’t known for sipping power, and a pair of Radeon X1800 cards is no exception. The SLI systems require less power at idle, and the GeForce 7800 GT in SLI doesn’t pull as much juice as the Radeon X1800 XL CrossFire under load. Nothing, though, eats up wattage like the dual GeForce 7800 GTX 512s in SLI, not even the Radeon X1800 XT CrossFire system.

A Radeon X1800 XT CrossFire rig is mighty fast. Also, it’s six degrees Fahrenheit outside right now at my place, and I’ve enjoyed the room-warming benefits of CrossFire and SLI systems throughout the preparation of this review. My mind boggles, though, when I try to consider the value proposition of plunking down $1200 for a pair of graphics cards and roughly $200 more for the motherboard. Could a pair of Radeon X1800 XT cards in CrossFire be a better deal than two GeForce 7800 GTX 512s in SLI?

Yeah, I suppose so, especially with GTX 512 prices currently in low-altitude orbit. I do have my reservations about CrossFire, including the hassle of dealing with external dongles and the iffy I/O performance of CrossFire motherboards that use ATI’s SB450 south bridge. Still, CrossFire performance generally scales well enough from one card to two, and I said in my initial CrossFire review that the long-term success of this solution would hinge on the quality of ATI’s new GPUs. Turns out that the Radeon X1800 XT is a very desirable graphics card that matches the GeForce 7800 GTX feature for feature and adds a few new wrinkles of its own, including finer threading granularity for Shader Model 3.0 and the ability to do antialiasing with high-dynamic-range rendering. The Radeon X1800 XT trails the GeForce 7800 GTX 512 in overall performance, but Radeon X1800 CrossFire may hit the streets at prices as much as $150 lower per card than the 7800 GTX 512. (Radeon X1800 XTs are already widely available at $599 or less.) In the rarefied air of big-money graphics subsystems, that potential $300 price difference—if indeed it develops—could make a Radeon X1800 XT CrossFire system a, uh, er, uhm, solid value.

Yeah, I said it.

It’s bitchin’ fast, at any rate.

Don’t go buying a Radeon X1800 XL card, however, expecting to add a Radeon X1800 CrossFire card later if you care at all about value. Dropping a $599 CrossFire card into your system and lopping off half of its RAM and much of its performance potential isn’t the brightest of moves. That solution sacrificies too much, in my view. You can get a dual-graphics solution involving a Radeon X1800 XL, but it’s far from optimal. Perhaps in the future, if prices drop dramatically on the Radeon X1800 CrossFire Edition cards, teaming one up with an XL could make some sense. That seems like a shaky prospect to me, though.

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Scott Wasson Former Editor-in-Chief

Scott Wasson Former Editor-in-Chief

Scott Wasson is a veteran in the tech industry and the former Editor-in-Chief at Tech Report. With a laser focus on tech product reviews, Wasson's expertise shines in evaluating CPUs and graphics cards, and much more.