Computer technology has gone through some major changes over the years, and while Voodoo’s offering pushed the multiple GPU method, their takeover by nVidia saw the technology belatedly appear years later. So how many GPUs can the motherboard support?
While modern motherboards can support two or more GPUs, and cryptocurrency rigs can have GPUs in the double digits, motherboards are best run with a single GPU. This is unless you’re doing specific tasks like video editing or need large GPU calculations.
Let’s look at how multiple GPU setups work, how to build one yourself, what to look for to ensure best performance, and the downsides to multiple GPU motherboard. We’ll also consider what boards and cards work best, and what the future holds for multiple GPU systems.
How Many GPUs Can a Motherboard Support?
Motherboards will offer varying levels of support for multiple GPUs. For modern computers, a GPU or video card is slotted into the PCIe (Peripheral Component Interconnect Express) slot on the motherboard.
Not all PCIe are the same, and depending on the manufacturer you may have the standard four PCIe slots which will then be organized by the speed of the slot. Typically, whatever PCIe slot is closest to the CPU socket will be the fastest.
You should always consult the manual to confirm this, or check for the 16x symbol on the board itself written next to or near the PCIe slot. This enables your video card to take advantage of the fastest speeds that your motherboard can enable.
As some motherboards will feature multiple PCIe slots, there is nothing stopping you from adding an additional GPU to the motherboard, or even up to six GPUs per motherboard for most medium- to high-tier motherboards.
Not every motherboard can support this, and some even go higher, particularly those like this ASUS B250 motherboard meant for cryptocurrency mining that can support up to 19 GPUs.
While technically many motherboards can support multiple GPUs, you’re not going to get that much of a performance boost unless you configure it properly.
Can You Put 2 GPUs on Any Motherboard?
If there are at least two PCIe slots on the motherboard, it will technically be able to take two GPUs.
Unfortunately, it is not so simple as just putting two cards in to get twice the power, because the cards have to be compatible with each other, your motherboard has to support dual GPU, and you’ll need to be running a modern operating system.
Just like with RAM, if you want to take advantage of a dual GPU setup, you’ll ideally want both GPUs to be the same: same model, same amount of video RAM, and same clock speeds. Technically a different brand won’t matter if the internals are identical.
Your motherboard will also need to support a dual GPU setup, which has different names depending on what card you want to go with. For nVidia cards, the technology is referred to as SLI, and for AMD cards it will be called Crossfire.
AMD has not really pursued Crossfire since the lack of success during the 2010s, and discontinued it in 2017.
You’ll need to pick up an SLI bridge for nVidia, either the Standard Bridge for supporting pixel clock speed up to 400 Mhz and bandwidth up to 1GB/s for an output of 1920×1080 through 2560×1440 at 60 Hz.
The High-Bandwidth Bridge will do 650 Mhz for 2GB/s bandwidth up to 5K and surround sound.
There will also be a bigger power drain so you’ll need to ensure you have a solid enough power supply unit to be able to deal with it, as well as featuring enough connectors.
Generally, you’ll want to be running at least Windows 8 to take advantage of a dual GPU setup, but Windows 10 or 11 is recommended for ultimate stability and compatibility.
What Motherboards Can Hold Multiple GPUs?
Any motherboard with multiple PCIe slots can technically hold multiple GPUs. You’ll typically have one GPU in the 16x slot and then the second below it in the 8x slot, connected with the SLI bridge. It is rare to find a 32x slot on a consumer grade motherboard.
Some possible choices include the ASRock X79 Extreme11 and the MSI MPG Z390 Gaming Pro, but you have to take into other factors such as which processor you will go with out of Intel and AMD.
It’s simple enough to look up the specifications on the manufacturer’s website or even the seller will put down the basic information including number and speed of PCIe slots.
Finding out whether a motherboard supports SLI or Crossfire will often require going to the manual or manufacturer’s website.
Is It OK to Use 2 GPUs?
While it may be OK to use 2 GPUs, in most cases you’re better off just using one, particularly if that means investing more into a single card than compromising and buying two weaker cards.
One issue that often arises is that it is not very straightforward to set up a dual GPU system, and even if you do get it working, it is not guaranteed to be compatible with every piece of software you deploy it with.
The doubling of the card doesn’t necessarily translate into a doubling for a single output or a summing of the video card speeds together. The way that VRAM works on a dual setup video card also means that only the primary card’s memory will be used.
Video cards have gotten massive over the last two years, crowding out the very limited space inside, so trying to fit two in there can be impossible, especially given how close the PCIe slots are.
GPUs also give off a lot of heat, and their proximity and power consumption can result in some unexpected premature aging of your other internals, causing performance degradation for the CPU, memory and other parts.
Further, while costs have been going up, supply of cards has also been fraught with competing demands from cryptocurrency miners and other supply chain issues, making the task of getting two compatible cards a pricey exercise.
Is Multi GPU Still a Thing?
It is safe to say that multi GPU is all but dead. While a single video card may have multiple cores on it as standard, the days of running video cards in parallel to get performance gains seems to be a thing of the past.
Apart from the heat and power issues as discussed above, the rising costs associated with GPUs means you’ll need to drop thousands of dollars just on acquiring two video cards, let alone the other important components such as a fast CPU, RAM, and a quality monitor.
The lack of developer support is one of the biggest reasons to avoid multiple GPU setups, as even modern games and operating systems don’t play well with such setups.
Unless you really have specific needs that call for multiple GPUs and you can afford to splurge on creating the surrounding environment to help it run, you’re much better off with a single, powerful GPU.
Gaming is best done on a single card, whereas video editing, multiple monitors, and large-scale rendering would be the best reasons to have multiple GPUs.
AMD stopped supporting it a long time ago, and since 2020 nVidia is not even putting SLI profiles to its GeForce driver packages, instead relying on the developers to do so. NVidia is not even offering the SLI bridge connectors on many new cards.
So you may end up with a dual GPU system that is just wasting power, causing damage to your rig, leaving performance on the table and cost an arm and a leg (as well as almost inevitable setup woes) to get working.
Does B450 Support 2 GPUs?
The B450 tends to come with a PCIe 3.0 16x slot as well as a PCIe 2.0 4x slot.
While this technically can support 2 GPUs, and the Gigabyte specifications reveal that it can handle Quad-GPU CrossFire and 2-Way AMD CrossFire technologies, it won’t be great performance due to the limited speed on the PCIe expansion slot. 
Will a 3060 Work on a B450?
As a B450 motherboard supports PCIe 3.0, it won’t take full advantage of the RTX 3060 but this is unlikely to actually translate into degraded performance. Otherwise it should work fine if you have a sufficient power supply.
The key to getting the most out of PCIe bandwidth is to have sufficient VRAM on the card, and with the RTX 3060’s 12GB of VRAM, this is very unlikely to cause any issues.
Can an Old Motherboard Support a New GPU?
The key to checking whether your motherboard will support a GPU is to look up the specifications of the motherboard and confirm whether it has a PCIe slot or not.
This has been standard for close to 20 years now, debuting with PCIe 1.0 in 2003, and the 6.0 standard being released in 2021.
Much like USB and other standards, the goal for PCIe was to make a compatible slot or socket that can take hardware for years to come no matter what crazy directions technology goes off in.
Older motherboards may have some issues in that they may throttle the card so that it can’t get to its full potential, but this won’t be a massive performance hit that is even noticeable.
The socket for the CPU will also limit what CPU you can put in there, further acting as a bottleneck to overall performance.
Modern GPUs have also become significantly bigger and heavier, so you may need to look at getting at a vertical GPU bracket or riser cable kit to accommodate it if your motherboard is old enough.