If you have been looking into multi-GPU setups, you are probably already familiar with the AMD CrossFire vs NVIDIA SLI debate. Both of these are technologies that allow two or more GPUs to work together simultaneously.
This article should help you understand how each works and which one might be better for you. Whether or not you actually need a multi-GPU setup is a different story, but we will come to that later.
What is AMD CrossFire?
CrossFire is an exclusive hardware technology by AMD that allows two or more compatible AMD GPUs to work in collaboration. This then improves both the quality of graphics and the overall performance that you get.
What is NVIDIA SLI?
SLI is, more or less, NVIDIA’s equivalent of CrossFire. However, SLI works exclusively with NVIDIA’s own GPUs. SLI, in its current form, has been around since 2004, but its underlying technology and the hardware it comprises of has improved considerably over the years.
Crossfire vs SLI: The Differences
On the surface, and to an average user, it seems like AMD’s CrossFire and NVIDIA’s SLI are the same technology other than the fact that they work best with each company’s respective line of GPUs. But once we begin to scrutinize the specifics, the two technologies begin to deviate. Some of these differences are covered below.
GPU Compatibility
CrossFire is can be used with GPUs that belong to the same generation. Other factors like different clock speeds, the manufacturer itself, RAM, etc. are not an issue. SLI, however, has a stricter set of prerequisites; which includes having two identical graphics processors. Clock speeds can be different and the manufacturer need not be the same (think EVGA, MSI, etc.), but an identical RAM configuration is still required.
For instance, you can pair an AMD Radeon RX 580 with an RX 570 if you are using CrossFire, but for SLI, you will need to have two NVIDIA GeForce GTX 1080 cards.
NVIDIA believes in ring-fencing the user experience. It limits compatibility in order to ensure consistency, whereas AMD prioritizes versatility and degree of options and has a less uniform user experience. Therefore, combining an NVIDIA GPU and an AMD GPU in a multi-GPU setup will not work regardless of the generation, model, and RAM; or whether you use Crossfire or SLI.
Bridging
NVIDIA requires an SLI bridge for both cards to be able to communicate. This is useful because it frees up bandwidth from the PCIe by acting as a physical connector between cards. By allowing them to communicate with each other over the bridge, it saves precious bandwidth on the PCIe lanes. AMD does not require a bridge.
Other Technical Differences
CrossFire works only in full-screen mode unless specifically engineered by developers to do otherwise. SLI is much more flexible and is compatible with windowed or borderless mode. NVIDIA also requires motherboards to be SLI certified, which is difficult for manufacturers because they must pay a fee for the license, as well as ensure that their PCIe slots to fit a set of specifications.
CrossFire compatibility is much less stringent; all that it requires of a motherboard is a pair of PCIe slots. This is why CrossFire enabled motherboards are more available at a lower cost and more easily.
SLI vs Crossfire: The Similarities
Since the core concept is more or less identical for both technologies there is obviously a significant overlap in properties, as described below.
SFR and AFR
SFR and AFR are both multi-GPU rendering modes. CrossFire and SLI use both modes.
SFR, or Split Frame Rendering, means that every time a frame is rendered, each graphics card will take half of it and render it separately. The two cards can act as one and pool their power together by taking up the top and bottom halves of the frame respectively.
On the other hand, AFR or Alternate Frame Rendering means that each card renders a whole frame; one renders the odd-numbered frames while the other renders the even-numbered frames.
Other Functional Similarities
Some other similarities are that both CrossFire and SLI allow dual, triple, or quadruple GPU setups. Both technologies are best suited for high resolutions and games that are graphically demanding. Even the critiques for both of these are similar because the core concept is identical.
Which One Is Best For You?
Both technologies are useful, and the one you pick will depend on your own needs. It is important to note, however, that the popularity of multi-GPU setups has been declining recently. If anything, they are more of a niche interest within the gaming hardware space at this point. If you have a powerful GPU, you may not even need to use such a setup. If you do decide to use one though, just be mindful of compatibility requirements before buying.
