External Graphics Card or eGPU. Tutorial and Basics

Today we present our Guide on eGPU or External Graphics Card to connect to our mini PC or laptop and improve performance in Gaming.

Thanks to this type of connections we can have a much higher performance than with the integrated GPUs mounted on the processors. As we will see we have multiple connection options, either using an M.2 PCIe slot, a USB-C cable or an OCulink connector. We show you what components you need and what alternatives we have for assembly.

Discover with us the performance improvement that can bring this system and how to mount it in the most economical way possible.

egpu review s001

Components to mount your External GPU

There are different alternatives to mount an eGPU, we can install it directly against the mini PC through an M.2 PCIe slot or use a USB-C or OCulink port if we have them available.

PCIe support for connecting a graphics card

Typically, eGPU brackets consist of a board with a PCIe slot with power connectors and an M.2 PCie card connector strip. There are also options that directly carry a USB-C or OCulink connector, and alternatives with a complete enclosed case. Hardware for attaching the GPU and a power cable for the GPU are included.

egpu review s013

There are several considerations to make before purchasing our eGPU bracket. If we are going to use an input port limited to PCIe 3.0 there is no need for a 4.0 card, for example.

  • Output speed of the board: PCIe 3x or 4x, depending on our mini PC or GPU to be mounted.
  • Ports: Select between M.2 PCIe, USB-C or OCulink output
  • M2 ribbon length: depending on our assembly we will need more or less length.
ATTENTION: The M.2 connector and the ribbon are delicate

egpu review s016

An important point is to know the electrical connectors on this board. On the left we start with the 8-pin connector to power the GPU with the included cable, then we have another 8 pins to use a DELL 12V 18A charger, 8 CPU 12V power pins and finally the 24-pin connector for ATX power supply.

egpu review s006

Power supply with ATX power supply

The easiest option to power our eGPU electrically is to use an ATX power supply, we have many options. The problem with this set is the volume it occupies and the wiring that we will have, you have to collect everything somehow without losing ventilation.

  • We must choose a power supply with the power required by the GPU we use.
  • ATX power supplies are cheap or we can use an old one.
  • Alternatively, we can use a smaller Flex ATX power supply.

egpu review s011

Power supply with DELL charger

An interesting option is also to use a DELL power supply of 216 W (12V 18A), these power supplies used in different devices historically are now sold second hand and are very compact.

  • The DELL 216 W 8 pin power supplies are available on AliExpress only for $49.
  • We are limited to a 200 W GPU with this power supply.
  • If we are going to use a very low power GPU, maybe we can even use a PicoPSU power supply.

egpu review s009

Connecting the External GPU

As we have seen, eGPUs must be connected to our mini PC or laptop. We have several alternatives, depending on our options we will choose one or the other.

  • When we connect it Windows will detect the GPU in the device manager and it will work directly.
  • It is necessary to have the NVIDIA or AMD drivers installed in the system previously.
  • Normally, the GPU will boot when the USB-C cable is connected to the motherboard. If it doesn’t work, you have to test by combining when you connect the power from the adapter or USB.

Connecting eGPU via M.2 PCIe slot

This is one of the most popular options for connecting an external graphics card. M.2 PCIe slots are very common nowadays and we can have efficient direct connection.

  • The M.2 PCIe slot should be of the highest possible speed, PCIe 3.0 or 4.0 by x8 or 16x,
  • We need a mini PC with two M.2 slots or change the storage to a worse SATA disk.
  • Check out the most popular mini PCs on our website for the latest offers.

egpu review s012

EGPU connection via USB-C or OCulink cable

If we do not have a free or fast enough M.2 PCIe slot, we can always use an M.2 to USB-C adapter that allows us to connect the eGPU by cable. We can use a USB 3.2 Gen 2×1 port up to 10 Gbps, but we recommend a USB-C Gen 2 2×2 up to 20 Gpbs or a USB4 up to 40 Gbps, depending on the power of the GPU in Gbps.

  • Normally, we will lose some performance by connecting an intermediate adapter.
  • As an adapter you need a M.2 USB4 reader with a fast chipset, for example we have tested the MAIWO 40Gbps with good results and it costs about $45.
  • It is necessary to use quality USB-C cables, we recommend USB4 cables for maximum compatibility, we have them on Amazon or AliExpress from about $15.
  • For adapters or eGPU support with OCulink we have fewer options, only recommended if we have a mini PC or laptop with this connector.

egpu review s007

External GPU Performance

Let’s see how an eGPU works and what are the performance limitations they have. Keep in mind that there is no universal standard to know the performance we are going to have, each hardware and game is a world, it will depend on the use of CPU, cables, adapters, chipsets and other factors.

Performance of an eGPU

For maximum performance use PCIe 4.0 x 16 or Oculink if available, as you can see thePCIe version and bandwidth determines the GB/sec speed available. Normally, the communication between CPU and GPU to make rendering requests depends on each game.

  • In the future, Thunderbolt 5 / USB5 will have better communication and more bandwidth.
  • Playing 4K HDR games with USB4 will have more performance limitations, we recommend 1080p.

External ports speeds

Port  Speed
USB 4 / Thunderbolt 4 40 Gbps = 5 GB/sec / 2x Lineas
USB 3.2 Gen 2×2 / TB 3 20 Gbps = 2,5 GB/sec / 2x Lineas
USB 3.2 Gen 2×1 10 Gbps = 1,25 GB/sec / 1x Lineas
USB 3.2 Gen 1×1 / USB 3.1 5 Gbps = 0,7 GB/sec / 1x Lineas
USB 2.0 High Speed 480 Mbps = 0.07 GB/sec
Oculink 64 Gbps sin adaptador / 32 Gbps con adaptador

PCIe and GPUs speeds

Modelo GPU Conector PCIe
NVIDIA 4090 / 4070 / 3070/ 3060
Radeon 7900 / 7700 / 6700
PCIe 4.0 x16 / 32 GB/sec
NVIDIA 4060 / 4070 / 3060
Radeon 7600 / 6600
PCIe 4.0 x8 / 16 GB/sec
NVIDIA 2060 / 1650 / 1060 /1050
Radeon 620 / 580 / 570
PCIe 3.0 x16 / 16 GB/sec

pcie lines

Overall eGPU vs discrete GPU performance

Summarizing the general concept, an eGPU can have a performance loss between 5% and 30% of its native performance in PC with current technologies, either by PCIe or USB-C. As mentioned, this is due to a number of connectivity and PC performance factors.

  • Example comparison with NVIDIA RTX 2060 on PC and as eGPU.

gow egpu

Notify of
Inline Feedbacks
View all comments
Would love your thoughts, please comment.x