SLI & Crossfire FAQ & Tutorial (NCIX Tech Tips #89)

# Understanding SLI and Crossfire: An In-Depth Guide

## Introduction

Today’s episode of NC TechTips is all about SLI (Scalable Link Interface) and CrossFire—two competing multi-GPU technologies. This video serves as an FAQ, addressing some of the most frequently asked questions about these technologies. Whether you're a gaming enthusiast or just curious about how multi-GPU setups work, this guide will help you understand the basics and more.

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## The Basics of SLI and Crossfire

The goal of both SLI (NVIDIA) and CrossFire (AMD/ATI) is to combine two powerful graphics cards to achieve better performance in 3D gaming. For example, using two NVIDIA GTX 480s or two AMD Radeon 5870s can theoretically double your performance compared to a single GPU setup.

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## Graphics Cards Compatibility

### Scenario 1: Different Models of the Same GPU

You can pair two different models of the same GPU. For instance, one card might have DVI, DisplayPort, and HDMI connectors, while the other has six mini DisplayPorts. They could also differ in VRAM (e.g., 1GB vs. 2GB), but as long as they share the same GPU core (e.g., AMD Radeon 5870 or NVIDIA GTX 480), they can work together in CrossFire or SLI.

### Scenario 2: Identical Cards from Different Brands

Two identical cards, such as two GTX 480s—one from MSI and one from Zotac—can run SLI without any issues. Even if the cooling solutions or PCB layouts differ, as long as the GPUs are the same, they will work together.

### Scenario 3: Different Coolers and PCB Layouts

Cards with completely different coolers and PCB designs can still function in multi-GPU setups, provided the GPU cores match (e.g., two GTX 460s). However, mixing older models like a GTX 460 with newer ones like a GTX 480 won’t work because their GPU architectures differ.

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## Motherboards for SLI and Crossfire

### Basic Configurations

The most common configuration is two-way SLI or CrossFire. Many motherboards, such as the Intel P55, support this setup using two PCIe x16 slots. While some boards may run these ports at half bandwidth (e.g., 8x instead of 16x), the performance impact is minimal and only noticeable in synthetic benchmarks.

### Enthusiast-Class Boards

High-end motherboards like MSI’s Big Bang X-Power or EVGA’s Classified x58 support three-way or even four-way SLI/CrossFire setups. These boards often have additional PCIe slots, allowing for more powerful configurations. For example, the EVGA x58 supports up to four GPUs, each running at 8x bandwidth.

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## Power Supply Considerations

Running multiple GPUs requires a robust power supply. A high-end setup with two or three GPUs can draw over 700-800 watts of power. Using an underpowered PSU (e.g., 500W or 600W) may result in instability or loud fans running at full speed. Always opt for a PSU that’s slightly larger than your needs to account for future upgrades and naturalPSU degradation over time.

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## Setting Up SLI and Crossfire

### Step 1: Check Motherboard Support

Ensure your motherboard supports the technology you want to use (SLI or CrossFire). Not all boards support both, so check with your manufacturer if unsure.

### Step 2: Purchase Matching GPUs

Buy a second GPU that matches your existing one in terms of architecture and core type (e.g., two AMD Radeon 5870s or two NVIDIA GTX 480s).

### Step 3: Install the SLI/CrossFire Bridge

Once both cards are installed, locate the SLI or CrossFire bridge that came with your motherboard or graphics card. Attach one end to each GPU. For a two-way setup, you only need one bridge; additional bridges are for three-way configurations.

### Step 4: Configure Your Drivers

Finally, update your drivers and enable SLI or CrossFire in the control panel. For NVIDIA, go to the “Set Up SLI” section and select “Maximize 3D Performance.” AMD’s setup is similarly straightforward.

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## Conclusion

SLI and CrossFire are powerful tools for gamers looking to maximize their graphical performance without breaking the bank on a single top-tier GPU. By pairing compatible GPUs, selecting the right motherboard, and ensuring adequate power supply, you can build a high-performance gaming rig that delivers stunning visuals and smooth gameplay.

Thank you for watching NC TechTips! If you have any questions or want more in-depth coverage of this topic, leave your comments below!

"WEBVTTKind: captionsLanguage: entoday's episode of NC techtips is going to be about SLI and Crossfire so these are two competing multi-gpu Technologies we're going to treat this as sort of an FAQ for some of the most frequently asked questions and the answers let's talk a little bit about the basic concept of SLI and Crossfire now everyone's trying to build faster and faster graphics cards all the time in fact here in front of me today I have the GTX 480 from Nvidia their fastest GPU and I have the radon 5870 from AMD their fastest GPU so what s Crossfire allows you to do is take one of these fastest gpus pair it up with another one and get better performance than you could possibly build on a single video card so you can see here the system I have on my right your left is running two gtx480 graphics cards that means in 3D games you are going to get in theory as much as double the performance from these these two cards running together as you could have with a single card one of the most common questions people ask me is which cards can I run together in SLI and I'm going to give you a bunch of different scenarios here that should explain all the different ways that you can take cards and put them together and get better 3D performance so first of all number one these are two radon 870s now they are not identical you can see that the end of this one has DVI connectors a display port connector and an HDMI connector and this one has six mini display port connectors now these two cards also have different amounts of ram this is a 1 gig card and this is a 2 gig card however these two can running Crossfire together because they both use a 5870 GPU now bear that keep keep that thought okay hold on to that thought I have two cards here these are both GTX 480s and they are identical cards they have the same outputs they have the same power connectors everything is the same except for one thing this one right here you can see is an MSI and I'm going to tilt up my test bed here so that you can see the sticker on the top of the other card this one is powered by Zotac so these two cards are identical but they're from a different brand they will run SLI just fine now I'm going to give you scenario number three these ones are the same brand these are both MSI graphics cards but they have different coolers they actually have completely different PCB layouts uh you can see that the twin frozer 2 card here is physically longer than the other card okay so these are are completely differently manufactured cards but they're both GTX 460s and I keep coming back to both the same GPU these will run SLI just fine so you can't take a 460 and run it with a 480 you can't take an Nvidia card run it with an ATI card the most important thing is making sure that you have matching gpus so that means you can have mismatch vendors mismatched Ram mismatched PCB layout none of that's important you just need to have the same GPU now that we've covered the graphics cards let's get into some detail about motherboards so I'm going to start with the most basic configur ation that you can use to run SLI or Crossfire this is a p-55 motherboard and it can run up to two-way SLI or two-way Crossfire that is two cards working together with its two PCI Express 16x ports now something I want to clarify I've gotten a ton of questions about this is what happens if your PCI Express 16x ports are only running at half the bandwidth adex because every p55 motherboard on the market has has this limitation where each graphics card gets only half the bandwidth when you install two now the reality of it is there is no performance difference except in highly synthetic benchmarks and even then it's very small so if you are running two-way Crossfire or two-way SLI a p-55 board is a great choice now the other board I have with me here today is a big bang X power this is from MSI that's actually the one that I have my test platform running on here I'm going to turn this to the side and I want you to take note of how many PCI Express slots there are on this motherboard you can't really see it very clearly but I'll explain there are actually six so because each of these cards is dual slot that means that if I moved over this card one I could actually install yet one more card so this one supports three-way SLI or three three-way Crossfire so that is three cards working together to produce the same 3D image now as far as I mean I can't even call this a a normal motherboard because this is an Enthusiast class board but as far as more normal motherboards go three-way is the most you can get except in some very very unique exceptions now this is an EVGA classified x58 four-way this motherboard is actually physically longer than a normal ATX motherboard and that's what allows you to be able to install up to four cards in this particular board now one last thing x58 does not have that same limitation of p55 so that's what allows you to take your PCI Express slots and split them more ways so you can either have two running in 16x or you can have four running in 8X 8X 8X 8X remember 8X doesn't really have a major impact on performance if you can measure it at all so that covers most of the motherboard Technologies to do with SLI and Crossfire now as you can imagine in the race to make faster and faster graph graphics cards we've had to cool them down and power them so you can see here I have an antech Quattro 1200 W power supply and the reason I mentioned that is because with s and Crossfire you can't be using the same entry-level power supply that you can if you're running a single graphics card so I've got my power meter here and I'm just going to lift this up so the camera can have a look we have actually seen the power draw of this system Peak above 800 watts were you looking when it went that high so above 800 Watts with an 80 plus silver Power Supply so that means that the power supply actually has to provide upwards of around 750 watts at Peak in a gaming scenario when you're running a high-end SLI or Crossfire configuration that means that bearing in mind that you don't want the power supply to run really loud so if you were to buy a 750 wat power supply to run this system it would be running at 100% whenever you're gaming which means the fan would ramp way up also remembering that a power supply doesn't necessarily provide its entire output for all of its life they tend to degrade a little bit so you always want to buy a power supply that's a little bit too big for what you're using now it gives you room to upgrade it gives room for it to degrade as it ages naturally and it's going to run a lot quieter and the last thing I want to cover briefly is how do I set up Crossfire SLI because I get these messages an awful lot so if you have one graphics card pretty easy make sure your motherboard supports the technology you're looking for because not all boards support both sing Crossfire the ones we've shown today do but not all of them do so check with your motherboard manufacturer next step is buy a matching GPU and we've already covered all of the requirements to make sure that your GPU or video card matches last but not least you're going to need an SLI or a crossfire Bridge so I'm just going to show you oh I dropped my keyboard on my phone that hurt that's okay I'm good so I'm going to show you very briefly how to do that once you've installed both graphics cards in your system you go into your motherboard box or your graphics card box sometimes it comes with either one you find the SLI Bridge or in this case Crossfire bridge and then you install it one Bridge onto each card okay now the cards may have two connectors you can see that these cards actually have two Crossfire connectors but that is for three-way configurations so when you're running a two-way configuration you only need one Bridge all right and last but not least you will need to go into your Nvidia or ATI driver and with both of them it's really simple because we have an Nvidia system running right now I'm going to show it to you on Nvidia but you go into the control panel you go into set SLI and because it's Nvidia also physics configuration and you go from disable SLI to maximize 3D performance and click apply that's it that's how simple it is to configure SLI and Crossfire is much the same thank you for checking out our episode today on SLI and Crossfire or uh multi-gpu Video Gaming Technologies if I wanted to be more professional soundingtoday's episode of NC techtips is going to be about SLI and Crossfire so these are two competing multi-gpu Technologies we're going to treat this as sort of an FAQ for some of the most frequently asked questions and the answers let's talk a little bit about the basic concept of SLI and Crossfire now everyone's trying to build faster and faster graphics cards all the time in fact here in front of me today I have the GTX 480 from Nvidia their fastest GPU and I have the radon 5870 from AMD their fastest GPU so what s Crossfire allows you to do is take one of these fastest gpus pair it up with another one and get better performance than you could possibly build on a single video card so you can see here the system I have on my right your left is running two gtx480 graphics cards that means in 3D games you are going to get in theory as much as double the performance from these these two cards running together as you could have with a single card one of the most common questions people ask me is which cards can I run together in SLI and I'm going to give you a bunch of different scenarios here that should explain all the different ways that you can take cards and put them together and get better 3D performance so first of all number one these are two radon 870s now they are not identical you can see that the end of this one has DVI connectors a display port connector and an HDMI connector and this one has six mini display port connectors now these two cards also have different amounts of ram this is a 1 gig card and this is a 2 gig card however these two can running Crossfire together because they both use a 5870 GPU now bear that keep keep that thought okay hold on to that thought I have two cards here these are both GTX 480s and they are identical cards they have the same outputs they have the same power connectors everything is the same except for one thing this one right here you can see is an MSI and I'm going to tilt up my test bed here so that you can see the sticker on the top of the other card this one is powered by Zotac so these two cards are identical but they're from a different brand they will run SLI just fine now I'm going to give you scenario number three these ones are the same brand these are both MSI graphics cards but they have different coolers they actually have completely different PCB layouts uh you can see that the twin frozer 2 card here is physically longer than the other card okay so these are are completely differently manufactured cards but they're both GTX 460s and I keep coming back to both the same GPU these will run SLI just fine so you can't take a 460 and run it with a 480 you can't take an Nvidia card run it with an ATI card the most important thing is making sure that you have matching gpus so that means you can have mismatch vendors mismatched Ram mismatched PCB layout none of that's important you just need to have the same GPU now that we've covered the graphics cards let's get into some detail about motherboards so I'm going to start with the most basic configur ation that you can use to run SLI or Crossfire this is a p-55 motherboard and it can run up to two-way SLI or two-way Crossfire that is two cards working together with its two PCI Express 16x ports now something I want to clarify I've gotten a ton of questions about this is what happens if your PCI Express 16x ports are only running at half the bandwidth adex because every p55 motherboard on the market has has this limitation where each graphics card gets only half the bandwidth when you install two now the reality of it is there is no performance difference except in highly synthetic benchmarks and even then it's very small so if you are running two-way Crossfire or two-way SLI a p-55 board is a great choice now the other board I have with me here today is a big bang X power this is from MSI that's actually the one that I have my test platform running on here I'm going to turn this to the side and I want you to take note of how many PCI Express slots there are on this motherboard you can't really see it very clearly but I'll explain there are actually six so because each of these cards is dual slot that means that if I moved over this card one I could actually install yet one more card so this one supports three-way SLI or three three-way Crossfire so that is three cards working together to produce the same 3D image now as far as I mean I can't even call this a a normal motherboard because this is an Enthusiast class board but as far as more normal motherboards go three-way is the most you can get except in some very very unique exceptions now this is an EVGA classified x58 four-way this motherboard is actually physically longer than a normal ATX motherboard and that's what allows you to be able to install up to four cards in this particular board now one last thing x58 does not have that same limitation of p55 so that's what allows you to take your PCI Express slots and split them more ways so you can either have two running in 16x or you can have four running in 8X 8X 8X 8X remember 8X doesn't really have a major impact on performance if you can measure it at all so that covers most of the motherboard Technologies to do with SLI and Crossfire now as you can imagine in the race to make faster and faster graph graphics cards we've had to cool them down and power them so you can see here I have an antech Quattro 1200 W power supply and the reason I mentioned that is because with s and Crossfire you can't be using the same entry-level power supply that you can if you're running a single graphics card so I've got my power meter here and I'm just going to lift this up so the camera can have a look we have actually seen the power draw of this system Peak above 800 watts were you looking when it went that high so above 800 Watts with an 80 plus silver Power Supply so that means that the power supply actually has to provide upwards of around 750 watts at Peak in a gaming scenario when you're running a high-end SLI or Crossfire configuration that means that bearing in mind that you don't want the power supply to run really loud so if you were to buy a 750 wat power supply to run this system it would be running at 100% whenever you're gaming which means the fan would ramp way up also remembering that a power supply doesn't necessarily provide its entire output for all of its life they tend to degrade a little bit so you always want to buy a power supply that's a little bit too big for what you're using now it gives you room to upgrade it gives room for it to degrade as it ages naturally and it's going to run a lot quieter and the last thing I want to cover briefly is how do I set up Crossfire SLI because I get these messages an awful lot so if you have one graphics card pretty easy make sure your motherboard supports the technology you're looking for because not all boards support both sing Crossfire the ones we've shown today do but not all of them do so check with your motherboard manufacturer next step is buy a matching GPU and we've already covered all of the requirements to make sure that your GPU or video card matches last but not least you're going to need an SLI or a crossfire Bridge so I'm just going to show you oh I dropped my keyboard on my phone that hurt that's okay I'm good so I'm going to show you very briefly how to do that once you've installed both graphics cards in your system you go into your motherboard box or your graphics card box sometimes it comes with either one you find the SLI Bridge or in this case Crossfire bridge and then you install it one Bridge onto each card okay now the cards may have two connectors you can see that these cards actually have two Crossfire connectors but that is for three-way configurations so when you're running a two-way configuration you only need one Bridge all right and last but not least you will need to go into your Nvidia or ATI driver and with both of them it's really simple because we have an Nvidia system running right now I'm going to show it to you on Nvidia but you go into the control panel you go into set SLI and because it's Nvidia also physics configuration and you go from disable SLI to maximize 3D performance and click apply that's it that's how simple it is to configure SLI and Crossfire is much the same thank you for checking out our episode today on SLI and Crossfire or uh multi-gpu Video Gaming Technologies if I wanted to be more professional sounding\n"