Date:
Friday , June 23, 2006
Author:
Brent Justice
Editor:
Kyle Bennett
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NVIDIA SLI & ATI CrossFire - Experiences & Opinions

Brent Justice talks about real-world experiences with SLI, CrossFire, and Dell’s 30” LCD. This is a free form editorial that simply gives you our opinions about high-end gaming as we see it today.

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Installation Experiences ATI CrossFire

With ATI CrossFire you have to install the cards in the correct order since one is a “CrossFire Edition” video card or what use to be called a “Master Card.” It seems ATI wants to move away from using the terms “Master” and “Slave” now, opting for “CrossFire Edition” and then your secondary card.

Now, this is reversed from what you had to do on the previous RD480 CrossFire chipset motherboards. Refer here and you can see how we set up Radeon X1800 XT CrossFire on that chipset. Note that the CrossFire Edition video card is in the PCI-Express slot farthest from the CPU, and the secondary card is in the slot closest to the CPU.

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With the new RD580 (Radeon Xpress 3200) chipset motherboards this has now been switched around. The CrossFire Edition video card needs to go in the primary (usually blue) PCI-Express slot which is closest to the CPU. Then you install the second X1900 series card in the secondary PCI-Express slot farthest from the CPU. If you do not install the cards in the right order you will not be able to enable CrossFire, so it is important you get this very basic installation order correct. Luckily the motherboard manual does indicate this on the ASUS A8R32-MVP, but if you are like me and don’t read the manuals you may put it in the wrong order going off of the information you knew to be true on the previous chipset.

Clean Out Your Drivers

A note to all CrossFire users, I personally have found it easier to go ahead and remove all drivers before installing a CrossFire setup and install both video cards at the same time instead of one at a time as directed. Supposedly one of the benefits of a dual GPU solution is that you can run on one video card now, and then upgrade later to multi-GPU performance by adding a second one, in this case the CrossFire Edition video card. In that case you’d already have the secondary card installed and you’d just have to switch their places and install the CrossFire Edition card with the drivers already in the system. I find that this sometimes causes trouble such as not being able to enable CrossFire.

For the best luck right out of the gate remove all drivers and clean those out of your system. Then download the latest driver package and put it on your desktop. Then turn off your PC, switch the cards around and install them both in the correct order. Then boot up with both cards connected and install the driver fresh and clean with both cards in the system. It should detect both cards at the installation and install drivers for both GPUs. At that point you can reboot and then you should be able to enable CrossFire with no problems. For our evaluations we have a ghost image setup where it has no drivers installed so we can ghost our system, install the cards, and install the drivers nice and fresh with no conflicts.

Install the Dongle

Once the video cards are physically in the slots and you have screwed them down in your case, you can then install the external dongle. Be careful, the dongle must also be installed in a certain way in order for CrossFire to work correctly. You need to have the dongle positioned so that the cable splitting off with the DVI connection for your monitor is positioned toward the DVI port on the CrossFire Edition video card. The picture below demonstrates.

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(Correct, Incorrect)

I did not try it in the incorrect orientation. The literature that came with our X1900 XTX CrossFire setup said to have it oriented a certain way so I stuck to that wanting to minimize my CrossFire difficulties and have the best performance. We will get to the dongle later.

Installation Experiences NVIDIA SLI

During our installations of CrossFire and SLI I found that I spent more time setting up CrossFire then I did SLI. SLI was much easier to install, it didn’t matter which order I put the video cards in because they were exactly the same. Therefore I put one in the primary PCI-Express slot and the other in the secondary PCI-Express slot. It also didn’t matter which orientation we had the SLI connector on top positioned in. We placed the SLI connector on top and pushed it down securely, SLI was now physically setup.

I really like the hard PCB SLI connector because it holds the two cards in place on our open motherboard system. Remember, it is up to the motherboard manufacturer to include the SLI connector and they choose what type. In fact there is a flexible SLI connector in existence. I personally have a 7” flexible SLI connector from NVIDIA which can be used if you do not have the spec part that came with the motherboard. The motherboard manufacturer should include the correct connector length with their motherboard depending on the width between the PCI-Express slots.