CrossFireX Arrives: First Look at 3 and 4 GPUs in 2 Card Setups
by Derek Wilson on March 7, 2008 12:05 PM EST- Posted in
- GPUs
… and Tearing it Down
Whether the problems we saw end up being very isolated problems or not, it's always good to be cautious. Now, let's move on to the part that will absolutely affect everyone who runs CrossFireX at some point: uninstalling the hardware. Until now, if we needed to step down to one card all we needed to do was remove the hardware and everything would be fine. AMD tells us that because CrossFireX uses Windows Vista's Linked Display Adapter (LDA) technique for combining multiple physical graphics cards into one virtual device, this is no longer as simple.
Before removing a card from the system, you MUST disable CrossFireX or uninstall the driver. If you do not disable CrossFireX, the driver will fail to load the next time the system boots. There will be no way (from what we can tell) to disable CrossFireX if the driver doesn't load. Thus, the driver will need to be uninstalled anyway. If you want to keep one card in the system, be sure to disable CrossFireX first or you will have to uninstall and reinstall your driver.
We've asked for more details about why this isn't something AMD can handle in the driver, and this is what we understand so far. After LDA mode is set up, a specific number of physical devices are expected when the driver tries to load. If there is only one card present, this looks the same as if the link failed and thus the driver won't load. AMD has said that this is the expected behavior based on how Vista handles LDA. Our position is that if this is the case, it is a design flaw in Vista that Microsoft needs to address.
After speaking with AMD on this, they have said they would try to make the documentation about how to handle uninstalling hardware properly as prominent as possible. While it's not ideal, thorough documentation of the issues is definitely a good thing to have when potential issues are very likely to arise.
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MAIA - Tuesday, March 11, 2008 - link
"After rebooting a few times to let windows do its thing, we installed the driver and all was well."This sentence is soooooo microsoft windows !!! :))
Sorry .... had to say it.
dash2k8 - Tuesday, March 11, 2008 - link
I'm just wondering: instead of piling on the number of GPU's, why hasn't a manufacturer just come out with ONE monstrous GPU that does away with the need of using multiple video cards? If someone is crazy enough to spend moola on 4 GPU's, I imagine that person would be equally willing to buy ONE card that has the same horsepower. Just saying.punko - Monday, March 10, 2008 - link
Thanks Derek for a good review. As you indicated, this may be the future and its good to see the tech reach a point where it is ready for use and can be improved upon as all tech goes forward.It also sound like you had a lot of help directly from AMD on this one.
gsellis - Monday, March 10, 2008 - link
"but today a WHQL drier is available "Hey Derek, typo in the beginning. Still mirthful about this one. Water cooling and you needed it drier to work with all GPUs?
ltcommanderdata - Sunday, March 9, 2008 - link
I'm just curious as to whether you've checked to see if quad channel memory has any benefit for multiple GPU situations? With 3 or 4 GPUs sucking data, I would presume the additional memory bandwidth provided by quad DDR2-800 would increase performance, especially since dual channel FB-DIMMs are not as efficient as the best dual channel DDR2 or DDR3 setups on desktop boards. It would be interesting to see the results of a 4x1GB setup on Skulltrail vs the 2x2GB setup you used.cerwin13 - Saturday, March 8, 2008 - link
Would it be wise to try this upgrade without SP1 installed with Vista 32? I am currently using 2x Radeon HD3870 x2s and would like to benchmark with these new drivers, but apparently SP1 isn't officially out yet?DerekWilson - Saturday, March 8, 2008 - link
other people had luck without SP1; it's not a requirement, but some of our editors did find that it helped with a lot of stuff ...you'll want to make sure you have hotfixes:
929777-v2
936710
938194
938979
940105
945149
as a minimum
Ananke - Saturday, March 8, 2008 - link
XFX has Forceware 169.32, my guess it was added after 9600GT appear. On Nvidia official download site the highest ver is 169.28Ananke - Saturday, March 8, 2008 - link
XFX has Forceware 169.32, my guess it was added after 9600GT appear. On Nvidia official download site the highest ver is 169.28Incisal flyer - Saturday, March 8, 2008 - link
Derek, thanks for the very timely and detailed review. I'm going to be building a system for Flight Simulator X and have been trying to figure out the best graphics card(s) for that application. Have you considered benchmarking that sim? A lot of discussion right now on AVSIM etc on what to do in terms of GPUs for people building new systmes. There is a lot of back and forth on advantages and disadvantages of different configs. I realize FSX is a bit of a niche product. Would FSX use multiple GPUs like 2 3870 x2s and are the potential headaches of that configurtation worth it if you are a not a computer geek? Or am I better off just getting a couple of Nvidia 8800s in SLI or a single 3870 x2 and not hassling with the 4 GPU solution? Any help or advice would be appreciated. Thanks in advance for your time.Incisal Flyer