Summary: In today's article we're evaluating ATI's X1950 Pro CrossFire, and find that while we like its built-in CrossFire support, all isn't perfect with the solution just yet. See how the X1950 Pro cards running in CrossFire mode compare against the GeForce 7900 GTX, Radeon X1900 XT, and GeForce 7900 GTO in this article!
The limitations of CrossFire
As an alternative to this, ATI has developed a CrossFire solution for cheaper, lower performance GPUs that doesn’t require the use of a CrossFire master card and CrossFire dongle. Instead data is sent over the PCI Express interface. This solution is far from ideal however, as performance is greatly compromised.
ATI’s Radeon X1950 Pro: 3rd-gen CrossFire
Fortunately the Radeon X1950 Pro is ATI’s first GPU with built-in support for CrossFire. No special CrossFire master card is necessary, as the technology is integrated into the GPU itself, so every Radeon X1950 Pro card supports the technology out-of-the-box.
At the top left corner of every Radeon X1950 Pro lies two 12-bit CrossFire connectors. This is one more connector than NVIDIA requires for SLI. In ATI’s case, the second connection technically isn’t required for today’s X1950 Pro CrossFire implementation (unless you plan on running CrossFire at 2560x2048 at some point in the future), instead ATI has added the second CrossFire connector for future applications where more than two graphics cards may be connected together. Say for instance if ATI were to launch a competitor to NVIDIA’s Quad SLI.
Rather than bundle the CrossFire cable with the motherboard, as NVIDIA and their board partners do with SLI, ATI will instead be including the CrossFire cable with the graphics card. Inside the packaging of each Radeon X1950 Pro card will be one CrossFire cable. When two cards are then purchased together, the end user then merely connects these cables together for CrossFire.
In terms of compatibility, ATI’s Radeon X1950 Pro CrossFire implementation is 100% compatible with all CrossFire-ready motherboards, including Intel’s 975X and P965 chipsets. All you have to do is install both X1950 Pro cards like you would normally, connect the CrossFire cables, and you’re good to go. ATI’s driver handles everything from there, including assigning one board as the master, and the second card as the slave. All the CrossFire rendering modes (scissor mode, alternate frame rendering, etc) carry over unchanged, as well as ATI’s Super AA feature, which brings 8x, 10x, 12x, and 14x AA settings to CrossFire users.
What we wanted to do with today’s article is examine the performance of ATI’s X1950 Pro CrossFire solution, and see how it compares with its intended competition, GeForce 7900 GS SLI. We’ve known for quite awhile that CrossFire’s Super AA modes give ATI’s CrossFire a decisive performance advantage in higher AA modes, but SLI beats CrossFire pretty much everywhere else. With the debut of the X1950 Pro’s internal CrossFire technology though, is CrossFire finally ready to take down SLI? Let’s find out!
Half-Life 2 Lost Coast
Again keep in mind that we’re testing the NVIDIA cards with the image quality setting at “High Quality” mode rather than the driver default setting of “Quality”. We’ve noted that the HQ setting significantly reduces the amount of texture shimmering in games such as Battlefield 2. This change does negatively impact NVIDIA’s performance, but it’s a tweak many NVIDIA users seem to be doing with their own cards so we’re doing it too. We’re also including XFX’s factory overclocked GeForce 7900 GS card, to represent the factory OC’ed 7900 GS cards. It’s not necessarily the highest OC’ed 7900 GS, but it provides a nice reference point to compare against.
3DMark 06 – Direct3D
Half-Life 2: Lost Coast – Direct3D
Quake 4 – OpenGL
F.E.A.R. – Direct3D
Oblivion – Direct3D
Oblivion – Direct3D
Call of Duty 2 – Direct3D
Far Cry – Direct3D
For the most part, performance is clearly scaling well with ATI’s third-generation CrossFire technology found in the Radeon X1950 Pro. Games such as Quake 4, Half-Life 2 Lost Coast, and Call of Duty all scaled similarly to what we’ve seen in the past from NVIDIA SLI and ATI’s 2nd generation CrossFire solution as implemented on cards like the X1950 XTX and X1800 XT CrossFire. As a result, the X1950 Pro CrossFire setup delivered performance that was superior to the GeForce 7900 GS SLI system in Lost Coast and Call of Duty 2, although NVIDIA’s advantage in Quake 4 allowed the GeForce 7900 GS SLI to outperform the X1950 Pro CrossFire cards in that title.
It looks like CrossFire isn’t scaling as well in F.E.A.R. though, the X1950 Pro CrossFire setup was barely faster than the single Radeon X1950 Pro at 1920x1200 for example. Far Cry didn’t seem to scale quite as well as we would have expected either considering the solo X1950 Pro’s performance. We’ve seen ATI’s 2nd generation CrossFire cards perform well in these tests in the past, so hopefully this is an anomaly that can be resolved in a future driver update. We’ll have to wait and see on that one though.
In games where CrossFire doesn’t scale at all, ATI provides the option of forcing AFR mode by switching the Catalyst A.I. slider from the default “standard” setting to the “advanced” setting. This was previously accomplished by renaming the executable file of D3D apps to "AFR-FriendlyD3D.exe". ATI’s solution still isn’t as elegant as NVIDIA’s SLI profiles, but based on our interview with ATI’s Godfrey Cheng earlier this month, we’ve got a feeling ATI is working as hard as they can to address this issue. Here’s a clip from the interview:
We’ll be curious to see what ATI comes up with in terms of game profiles, as clearly it’s a feature that would be great to have.
Overall though, we really like what ATI has pulled off with the Radeon X1950 Pro’s internal CrossFire connection. If ATI can get the scaling issues we ran into with F.E.A.R. and Far Cry resolved, ATI enthusiasts will finally have a viable alternative to NVIDIA SLI that won’t come with all the drawbacks CrossFire has endured in the past.
|© Copyright 2003 FS Media, Inc.|