ATI has been particularly quiet regarding CrossFire since their launch at Computex back in June. I assumed that we wouldn't see CrossFire boards and cards until August or September at the earliest, and it's really starting to look like that's going to be the case. But I'm not here to talk about CrossFire availability, I'm here to talk about performance.
There have been a number of CrossFire previews published all over the net, including our benchmarks from Computex. But what truly caught my attention was the tests over at HKEPC that showed two X700 cards working in CrossFire mode with nothing more than a simple BIOS update, no master card needed.
Something about that just didn't make much sense; ATI went through all the trouble to stick a compositing chip on these CrossFire master cards, and all you really need is the BIOS from a master card? So we did some digging and Wesley actually discovered the truth behind current CrossFire performance.
ATI distributed a special driver to their partners prior to the Computex launch that was designed to simulate CrossFire performance, by only rendering odd frames (effectively doubling the frame rate and simulating AFR performance). Although we can't confirm that we also ran with this driver back at Computex, chances are we probably did. But more importantly, the reviews you've seen where a pair of slave cards are used aren't actually testing CrossFire, they are simply simulating the performance of CrossFire by rendering half the frames.
We have learned however that the performance of this special driver is actually virtually identical to AFR performance with CrossFire actually working, but it is important to understand that when CrossFire is eventually released - you won't be able to just flash the BIOS on a slave card and have it work as a master card. And obviously, you won't be able to use just any cards in CrossFire mode, you'll have to stick with a X850 or X800 master card.
Although I have yet to see final benchmarks, my guess right now is that ATI needs to actually release CrossFire when they've shipped R520 boards. Had NVIDIA not launched G70 it wouldn't have been as big of an issue, but with a single G70 basically equal in performance to a pair of 6800 Ultras, ATI isn't winning any brownie points by competing with yesterday's GPUs. I think a launch/shipping announcement of R520 and CrossFire either sequentially or simultaneously would put ATI's best foot forward, as CrossFire has lost a bit of its steam by this point.
There have been a number of CrossFire previews published all over the net, including our benchmarks from Computex. But what truly caught my attention was the tests over at HKEPC that showed two X700 cards working in CrossFire mode with nothing more than a simple BIOS update, no master card needed.
Something about that just didn't make much sense; ATI went through all the trouble to stick a compositing chip on these CrossFire master cards, and all you really need is the BIOS from a master card? So we did some digging and Wesley actually discovered the truth behind current CrossFire performance.
ATI distributed a special driver to their partners prior to the Computex launch that was designed to simulate CrossFire performance, by only rendering odd frames (effectively doubling the frame rate and simulating AFR performance). Although we can't confirm that we also ran with this driver back at Computex, chances are we probably did. But more importantly, the reviews you've seen where a pair of slave cards are used aren't actually testing CrossFire, they are simply simulating the performance of CrossFire by rendering half the frames.
We have learned however that the performance of this special driver is actually virtually identical to AFR performance with CrossFire actually working, but it is important to understand that when CrossFire is eventually released - you won't be able to just flash the BIOS on a slave card and have it work as a master card. And obviously, you won't be able to use just any cards in CrossFire mode, you'll have to stick with a X850 or X800 master card.
Although I have yet to see final benchmarks, my guess right now is that ATI needs to actually release CrossFire when they've shipped R520 boards. Had NVIDIA not launched G70 it wouldn't have been as big of an issue, but with a single G70 basically equal in performance to a pair of 6800 Ultras, ATI isn't winning any brownie points by competing with yesterday's GPUs. I think a launch/shipping announcement of R520 and CrossFire either sequentially or simultaneously would put ATI's best foot forward, as CrossFire has lost a bit of its steam by this point.
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jkostans - Tuesday, July 19, 2005 - link
If you are looking for a high end card now, it would be stupid not to wait for the R520 to come out. If it's better then get that, if it's worse, then the 7800 will be cheaper. Oh and crossfire/sli is a waste of money no matter how you look at it. The next gen product will always match or come very close to exceeding the performance for a lot less. (not to mention the rediculous power requirements)Anonymous - Tuesday, July 19, 2005 - link
It all depends on what market you are in. Nvidia is the top performer if money is not an issue via sli or the new gtx. Bang for the buck is ati...a x800xl outperforms a 6800GT at a lover price.Strages - Tuesday, July 19, 2005 - link
#22, you make me cry.SLI has sold well into the millions of units. The 6600GT is the most popular card on the market, and there are many out there with SLI systems based on these.
First, the nForce4 is the most successful chipset launch ever by nVidia, even beating out the nForce2 in both launch partners and volume. Secondly, being the fastest, most feature-rich, and most overclockable chipset on the market (or even ever, comparatively) is far from buggy. NForce4 has dominated the AMD market and has set itself up to dominate the Intel enthusiast market as well.
The 7800GTX is actually starting to sell pretty well for a ultra high-end card.
And last but not least, AGP-based cards use the same amount of power as PCIe-based cards, they just pull power from different places (PCIe supplies 75w through the slot vs. 25w for AGP slots).
Careful ElJefe, your fanboy is showing.
ElJefe - Tuesday, July 19, 2005 - link
AGP is the same speed as pci-e.hardly a soul besides a minute percentage of people ever get another video card for sli. Really, there has been no point besides for about 3 months a year ago almost to even use 2 cards. invidia 6600GT was only thing worth it, but people said, ehhh.... screw it lets get a 6800GT or ultra and see if I can rake up some cash for another one, if not, i still go above 70 frames for the games out there at highest resolutions.
then the 7800 comes out. blowing away any sli. and, no game really needs it. I mean, no normal person with a monitor under 23 inches needs it.
ATI makes all-in-wonder cards, also, the 2d text is better, and, agp chipsets use about 40 watts less of power without being slower than 1-2 frames at maximum compared to actively cooled/noisy nforce 4 sli chipsets, which, are also buggy still comparitively.
the new ULI one is king if it comes out to market soon. runs pci e and agp at full tilt.
(agp is all-in-wonder besides the severely slow x600 which wouldnt pass for a 9800 pro even)
dornick - Monday, July 18, 2005 - link
This is the most ridiculous thing I've ever heard. Let's simulate Quad-Crossfire!!! by rendering only an eighth of the frames!!!d_jedi - Monday, July 18, 2005 - link
I'm willing to wait for R520.. ATI better have something good, though!sixpak - Monday, July 18, 2005 - link
#18 No this is irrelevant. Similar to Sony PS3 stunt to get people wait on ATI while Nvidia actually has something shipping. Why irrelevant? Well it's business as usual, don't get so worked up over it. When the product is here for real, then it's time.geo - Sunday, July 17, 2005 - link
Yes, #15 & #17 are the crux of the matter. Which is the right view? It makes a difference.
Daniel - Sunday, July 17, 2005 - link
#15 - you should read anands post more carefully."ATI distributed a special driver to their partners prior to the Computex launch that was designed to simulate CrossFire performance, by only rendering odd frames (effectively doubling the frame rate and simulating AFR performance). Although we can't confirm that we also ran with this driver back at Computex, chances are we probably did. But more importantly, the reviews you've seen where a pair of slave cards are used aren't actually testing CrossFire, they are simply simulating the performance of CrossFire by rendering half the frames. "
nothing about rendering even frames here. see, doubling the rate assumes no overhead whatsoever, which is rediculous. first of all you are using double the bandwith to get the memory info to both cards. then, AFR isnt as simple as saying you, render odd, you, render even - it has to go through careful load balancing to figure out what the overall frame rate is, and where to render and skip, and then what is odd and even. easier said then done. then, this all has to be sent accross the, er, dvi/whatever weird interface they call it and put back together into a single coherent video stream. all that needs processing time/bandwith and will take away more then a few FPS. thats why double is not realistic, not on SLI, not on crossfire - ati just doubling the framerate is lying
reactor - Sunday, July 17, 2005 - link
Well I agree with you, i dont think anyone in there right mind sould spend $350 on an agp card. I meant more along the lines of those who are on old tech already and looking for one last upgrade just to keep them going till they can get the new system. Remember most people still on agp will have to upgrade to s939 from what they are on. So its not just buying a new motherboard and gpu, its also cpu, maybe even more. With these ULi boards just reviewed that may be a better upgrade path for those trying to migrate.Basically i meant ati needs all the help they can get right now, and keeping the agp market open may be beneficial to them.