5 Ways to Know if Graphics Card is Compatible With Your MB

If you are new to PC building or if you are planning on upgrading your GPU, then you can get confused on how to know if graphics card is compatible with your motherboard and PC or not.

Basically, there is no hard and fast rule to check whether a graphics card is compatible with your PC or not. Instead, you have to check a couple of factors, some of which are important while others are recommended in order to see if the GPU will work with your PC optimally or not.

For instance you have to check whether you have a free PCIe x16 slot, sufficient power and sufficient space in the chassis for the graphics card.

In order for the GPU to run optimally, you also have to check the PCIe version of the GPU and that of the motherboard. You have to also ideally ensure that your CPU does not bottleneck your graphics card’s performance.

The good news, however, is that due to the flexibility of PC interfaces, you should be able to run the latest graphics card on a PC that is even a decade old (given that enough power is supplied). 

Whether you can run the new graphics card optimally is another question which we will explore below.

Also Read: How to Check What Motherboard You Have?

How to Know if Graphics Card is Compatible With Your Motherboard?

In order to check if graphics card is compatible with your motherboard or PC, you have to check for 3 important and 2 optional (but ideal) characteristics and specifications:

  1. Important: A Free PCIe x16 Slot
  2. Important: Sufficient Power and PSU Cables
  3. Important: Enough Space in the Case/Chassis
  4. Ideal: The PCIe Version of Motherboard and GPU Must Match
  5. Ideal: A CPU That Does Not Bottleneck Your GPU

Let us explore each of these points below.

1. A Free PCIe x16 Slot

For starters, you need to make sure that your motherboard has a free PCIe x16 slot with 16 PCIe lanes ideally.

x16 slot pcie
A PCIe x16 slot with 16 lanes

PCIe lanes are basically information highways for connecting PCIe devices to the CPU. The more lanes a slot has the more demanding card you can install.

GPUs generate a lot of data and thus ideally demand an x16 slot with 16 lanes – but can also work on a PCIe  x16 (x8) slot. If you are confused about this, read on.

Also Read: What are PCIe Slots?

A PCIe x16 Slot Can Have Different Lane Counts.

Not all PCIe x16 slots are created equally. Some feature a full 16 lanes, others may feature 8 or even 4 lanes.

Have a look at the motherboard below. You can see that the bottom x16 slot, despite having the full size, features only 4 lanes – which is far less than the ideal requirement of 16 lanes by a GPU.

does it matter which pcie slot I use w
PCIe Slots for adding expansion cards. Note that the bottom x16 slot actually only has 4 lanes. You can figure this out by reading the specsheet of the motherboard. You would use the top x16 slot for your GPU in the case of this motherboard

Hence installing a GPU on this slot is not recommended at all. In fact, NVIDIA graphics card have a minimum requirement of an x16(x8) slot or 8 lanes. AMD graphics card can work on x16(x4) slot but its performance will be heavily bottlenecked when working on 4 lanes.

Also Read: Can a Motherboard Bottleneck a GPU?

There are two studies that I would like to point to for you to understand the impact different lane count can have on GPU performance.

The first is by Gamer Nexus. According to their study for gaming, if you have a SINGLE graphics cards then using it on either x16 or x8 would have minimal impact.

PCIe lanes difference x8 x16
GPU Performance on Gaming on x16 and x8. Source: Gamer Nexus

The second study is by Pudget Systems which is a bit more comprehensive. They tested not just a single but single AND dual graphics card setup on x16/x16, x16/x8 and x8/x8 configuration.

According to their study, depending upon the applications you use, their can be a great impact. For gaming, the impact is nominal (within 3-5%), but for professional software and benchmark engines, the performance drop can be as high as 30%. 

TL;DR: Always use the top PCIe x16 slot for your graphics card as it almost always features the full 16 lanes.

Also Read: Does it Matter Which PCIe Slot I Use?

2. Sufficient Power and PSU Cables

The second important aspect to look is the power requirement of the graphics card and making sure your Power Supply Unit can deliver it.

Newer and beefier graphics card have a very heavy power requirement. To figure this, you simply have to check out the specsheet for your GPU. 

How to Know if Graphics Card is Compatible With Your Motherboard
NVIDIA RTX 3080 Power Requirement and Connectors Required. Source: ASUS

Almost all graphics card have a recommended PSU given. The ASUS TURBO V2 RTX 3080 recommend having a PSU with a rating of 850 Watts.

Recommended PSU is NOT Equal to Consumed Power

The recommend PSU rating does not relate to the power consumed by graphics card. It relates to the Power Supply Unit that is ideal for the entire build and the rest of the components such motherboard, CPU, RAM, drives, cooling solutions.

To figure out the power requirement of the GPU, you have to look at the Power Connectors it requires. The GPU shown above has a requirement of 2 x 8 pin connectors. 

Each 8 pin connector provides 150 Watts of power and the PCIe slot itself provides 75 Watts of power. Therefore the graphics card above requires 375 Watts of power (2x150W + 75W)

The following chart summarizes power requirement based on power connectors specified.

PCIe x16
6 Pin Cable
8 Pin Cable
12 Pin Cable
Max Power
75W1 x 75W00150W
75W01 x 150W0225W
75W2 x 75W00225W
75W1 x 75W1 x 150W0300W
75W02 x 150W0375W
75W1 x 752 x 150W0450W
75W03 x 150W0525W
75W001 x 600W675W

You Must Have Sufficient and All the Required Cables

PCie Power Cables
PSU must have all the required power supply cables.

Your Power Supply Unit must have all the required cables in order to power up the GPU.

For instance, if your GPU requires 2 x 8 pin connectors, you have to have both 8 pin connectors connectors. You cannot have only 1 plugged or have 1 connected with 8 pin plug and the other with a 6 pin plug.

graphics card connected
This GPU requires 2 x 6 pin. Both of them are connected.

If in case your PSU does not have required plug, then you will need to get adapters or splitters.

Understanding the power requirement and cable requirement is an essential consideration for knowing if graphics card is compatible with your motherboard and PC.

Also Read: What are PCIe Cables Used For?

3. Enough Space in the Case

It goes without saying that the PC case should have sufficient space in order to accommodate your graphics card.

In addition to that, you must also note that sometimes installing a graphics card can render another PCIe slot inaccessible.

Therefore, you may have to move your connected devices around. 

The following image shows a connected graphics card blocking TWO x1 slots underneath.

PCIe slot configuration
graphics card blocking x1
The graphics card is blocking two x1 slots underneath it.

As such, if you have additional card installed such as a WiFi card, on the x1 slot, they will need to be moved to different slots and if no slots are available, then you may have to sacrifice an expansion card by removing it.

Sizes of Graphics Card

There various sizes of graphics card identified by how many PCIe slots worth of space they occupy. So a graphics card with 1 profile occupies 1 PCIe slot worth of space. This would not block any other slot. Similar a 2 profile GPU would occupy 2 PCIe slot worth of space.

Here is a break down of different sizes you can find for GPUs.

  • Low Profile: 1 and 1.5 slot
  • Average: 2 and 2.5 slot
  • Large: 2.7 and 3.0 slot

You can figure out the size of the GPU before purchasing by looking at its specsheet.

RTX 3080 Slot Size
ASUS Turbo Geforce RTX 3080 V2 occupies 2 slots

Some smart motherboard designs often have PCIe slots intended for GPUs at a distance from other PCIe slots so that nothing is blocked.

Also Read: How to Check Which Graphics Card is Being Used?

4. Ideal: The PCIe Version of Motherboard and GPU Must Match

This is also a very important consideration particularly nowadays as PCIe 4.0 is becoming widespread and PCIe 5.0 is around the corner.

With every PCIe version, the transfer speed of the slot doubles. Meaning a PCIe x16 v4.0 slot can transfer a lot more data as compared to PCIe x16 V3.0 slot.

Hence, the devices built for the v4.0 PCIe protocol can be much more powerful compared to 3.0 devices. 

Which is exactly what you should take note of. Since majority of the older systems still conform to version 3.0, installing newer PCIe 4.0 GPU on a PCIe 3.0 slot can present performance bottlenecks.

 You can generally figure out the PCIe version of your GPU by checking out its specsheet. Essentially, the NVIDIA RTX 3000 series and AMD Radeon RX 6000 series and newer support PCIe 4.0.

PCIe is Backwards Compatible – PCIe Version and Performance Bottlenecks.

Again, while the PCIe interface is backwards compatible – meaning newer PCIe 4.0 cards CAN work on older 3.0 slots, it is ideal that you must match version of the graphics card and the slot.

PudgetSystems.com actually conducted a study on this whereby they tested an RTX 3090 (V4.0 device) and a Titan RTX (v3.0 device) on PCIe 1.0, 2.0, 3.0 and 4.0 x16 slots.

The following graphics shows the results:

Davinci Resolve PCIe testing

Image: PudgetSystems.com. Comparison of how RTX 3090 and Titan RTX perform on different PCIe generations. A significant impact can be seen on performance in DaVinci Resolve (video editing software) when using the cards in older PCIe slots.

It is clear that a PCIe 4.0 GPU (RTX 3090) gains performance if installed in a PCIe 4.0 slot but looses performance when installed in older slots.

At the same time you can see that a PCIe v3.0 GPU (Titan RTX) does not gain performance if installed in a newer v4.0 slot.

Also Read: Can You Use AMD GPU with Intel CPU?

5. Ideal: A CPU That Does Not Bottleneck Your GPU

Finally, you must make sure that there is parity between the graphics card and the CPU. 

Meaning if you have a high end NVIDIA RTX 3080, it would be unwise to pair it with a mere Intel Pentium CPU. Should at least get a Core i5 or Ryzen equivalent.

The following video shows how the performance of a graphics card gets impacted when using weaker CPUs. 

A CPU may not have a direct link for knowing if graphics card is compatible with your motherboard, but pairing the right CPU matters. 

Also Read:

Final Words

So how to know if graphics card is compatible with your motherboard and PC.

Well, given the flexibility and modular design of motherboards, it is a highly probable that your graphics card would be compatible with your motherboard even if its a decade old.

But the better questions to ask are how to know if your GPU will work OPTIMALLY on your motherboard or how to make the right PC build with a graphics card. Because here, you have to take note of bottlenecks caused by PCIe version, PCIe lanes, CPU and also consider the size and power requirement.

Also Read: How to Check SSD Compatibility With Laptop or Desktop?

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Atif Qazi
Atif Qazi is the founder of PCGuide101 and an expert in the computer peripheral industry with over two decades of experience. He has worked as a consultant for major companies and has a deep understanding of the inner workings of computer peripherals. He has a degree in Electrical Engineering and has served as a product manager and technical consultant. He is passionate about testing and evaluating the latest products to provide readers with reliable information.

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