What is a PCIe Cable Used for: Type and Speed Compare

Maria D. Stephens

As an expert in tech, you will typically find numerous daily inquiries about PCIe cables, and some of the few questions you will typically find are: What exactly are PCIe cables? Or where should PCIe cables connect, or how do you plug in a PCIe cable? All these questions are well answered if someone first gets to understand what is a PCIe cable.

To learn about the PCIe cable, we can explain it as an independent 8-pin power connection connecting the graphics cards directly to the power supply. Some wires usually are 6-pin or 6 + 2-pin and 8-pin PCIe cables. Just to make it easier for any beginner who is new to PCIe cables, these cables serve the purpose of supplying power to high-performance graphics cards. Therefore, these cables draw electric power directly from the PSU  while its other end securely attaches to the graphics card's designated power connector.

We will discuss what a PCIe cable is and where it is used so that you can comprehend its usage, especially when performing an upgrade PC. It is expected that when you upgrade, you will have high-performance graphics cards, which tend to acquire a substantial power consumption. In this article, we will dive into the significance of PCIe cables, addressing a few topics concerning PCIE cables.

Table Of Contents

What are PCIe Cables?

PCIe cables are integral components of the power supply Unit(PSU), and their primary function is to provide power to PCI cards that require additional power, such as high-performance graphics cards.

To understand further how PCIe cables work, we can look at Standard PCIe x16 slots; there is a provision for supplying 75 watts of power to the PCI Express expansion cards you install. So, the power supplied is sufficient for running low-power demanding graphics cards or other expansion cards like sound cards or network cards. What if a user uses graphics cards that consume more power, like the Nvidia GeForce RTX 3060 Ti, what do you think you will have to do? You will need to use PCIe cables to provide some supplemental power.

So, to be on the safe side and to know whether to use PCIe cables or not, it will be essential for you to consider your power requirements and understand how many and what types of PCIe cables you will need before purchasing your supply unit. If you have a plan like this, you will be assured your system can adequately support and power all your components.

PCIe Generation Compared.

As technology advances as time goes  also it applies to the PCIe cables, which have evolved from five generations. Starting from PCIe 1.0, 2.0, 3.0, 4.0, and 5.0. So, in each generation, the Bandwidth also doubles. Therefore, if you use the PCIe cables, it is good to note their age. If you use a PCIe 2.0 in a slot of 4.0, you will still get the 2.0 performance. Here is a table summarizing the oldest to the current available generation.

Row 0 - Cell 0 Bandwidth Gigatransfer Frequency
PCIe 1.0 8 GB/s 2.5 GT/s 2.5 GHz
PCIe 2.0 16 GB/s 5 GT/s 5 GHz
PCIe 3.0 32 GB/s 8 GT/s 8 GHz
PCIe 4.0 64 GB/s 16 GT/s 16 GHz
PCIe 5.0 128 GB/s 32 GT/s 32 GHz
PCIe 6.0 256 GB/s 64 GT/s 32 GHz

Types of PCIe cables available.

As you can see, various PCIe cables are available in the market, and not just one. With the types of cables available, you need to know how to differentiate them. Also, a critical aspect of these cables is that the number of pins and the maximum power they can deliver depends on the types of  PCIe cables. The most common cables you can generally find in the markets are available in 6, 8, and 12-pin; the most popular used is the 8-pin cable. So, let's have a look at these cables and their uses.

i. 6-Pin Power Cables.

For 6-pin power cables, these cables are mainly designed to deliver a maximum power output of 75 watts. They are typically used to provide power to graphics cards that have lower power requirements.

ii. 8-pin Power Cables.

Another type of PCIe cable is the 8-pin Power Cable, which can supply up to  150 watts of power, making them the most suitable cable for high-performance gaming rigs and mining set-ups. For graphic cards, you can also use an 8-pin power cable that is essential for a substantial amount of power. You can find these cables in straight 8-pin and 6+2 configurations.

iii. 12-Pin Power Cables.

A 12-pin PCIe cable can deliver a maximum power output of 600 watts, depending on the specific cable. The primary function of these cables usually  is used in scenarios like overclocking and mining, where a significant amount of power is needed.

iv. Pigtail Power Cables.

One feature when you use a pigtail PCIe cable is that it has one end that connects to the power supply, and the other end splits into two cables. The splitting of the cables mostly depends on the model so that they can be divided into two 6-pin or 8-pin connectors. When you select these cables, be aware that they are suitable for powering low-power graphics cards but are not recommended for high-end graphics cards due to their lower power output than straight cables.

The power socket on the PSU side is responsible for supplying power to the graphics card, labeled as PCIe /CPU or VGA. The connector cables are also labeled as "PCI-E", and it is advised whenever you consider purchasing additional cables for your graphics, It is good if you acquire them from the same PSU manufacturer.

Another thing that is crucial for users to understand is that when you select the PSU to use, it needs to includes an adequate number of PCIe cables to connect to your graphics cards. Also, it is suitable for any user to differentiate the PCIe cable connector from the ATX12V/ESP12V connector for the CPU. This is because the two connectors look similar.

How many PCIe cables do I need?

Determining the number of PCIe cables you need depends mainly on the specific equipment you have with you. Before deciding on the PC design process, you should ask yourself this question before starting. First, you must consider how many and what sort of GPU you intend to utilize in the future and if you want to overclock. You may not need to use any PCIe power cables at some point this is due to; for instance, if you have a GTX 1050 Ti 4 GB, it only draws 75 watts of power and may not need a dedicated PCIe power cable. For those who are not gamers and won't go for high-power graphics cards in future, then you don't have to have a PCIe power cable. You will only need a PCIe x16 slot to provide power for the graphics available.

You may need a PCIe cable when you have a GPU such as the Radeon HD 7970 X2 with a listed TDP of 500 watts; you will typically require three PCIe 8-pin power connectors. When you calculate the total power consumption, you will find that each 8-pin connector can provide up to 150 watts, which results in a total of 450 watts(150W + 150W + 150W). Including the PCIe slots in the motherboard can supply around 75 watts, up to 525 watts, to meet the GPU's power requirements.

Those thinking of constructing a mining rig that will need high-end GPUs will need three 8-pin PCIe cables that will invest in a high-capacity model power supply unit. The PCU should be accompanied by other power sockets, enabling you to connect precisely the required number of PCIe cables. So, in the future, if you feel like adding more graphics, you will simply insert an additional cable or two.

What to do if you lack a PCIe cable?

Not all PCs have a PCIe cable. Some of the old PCs do lack the PCIe cables. In this case, you may wonder what you can do next. Don't worry since we have an alternative solution where you can purchase a Molex to PCIe cable adapter. Most users with old PCs have improvised their machines by inserting many Molex connectors, an excellent alternative for PCIe power connectors.

So, if you use Molex connectors, remember they have a 54-watt power rating. Therefore, connecting 2 Molex to 1 PCIe power cable 6-pin will be great. If an 8-pin PCIe power line is required, the calculation should be based on determining the required wattage and GPU thermal design power (TDP).

How do I connect a PCIe cable to my GPU?

To connect a PCIe cable to my GPU, first turn off your computer and unplug it from the power outlet. Find the PCIe power connectors on your power supply and your graphics card. These PCIe power cables on your graphics card are usually located on the end of the card, near the PCIe slot. Ensure the connectors are the same size and shape and match them to the PCIe power connectors on your power supply.

Insert the PCIe power connectors into the PCIe power connectors on your graphics card. Secure the PCIe power connectors in place with the screws provided, and make sure not to force anything. Turn on your computer to ensure that your graphics card is powered correctly. If successfully connected, your GPU will run smoothly, thus improving your computer performance.


Understanding the different power cables, such as 6-pin, 8-pin, and 12-pin in PCIe cables, is crucial for effectively powering graphics and other high-power devices in your computer. PCIe cables provide the power that these graphics cards need to operate. The choice of the appropriate cable depends on your hardware's power requirements. It is also essential to pay attention to the markings on the PSU and cable connectors to ensure proper compatibility. Investing in a modular power supply unit with ample PCIe cable connectors will provide flexibility and scalability when planning a mining rig or high-performance gaming set-up.

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