What Are PCIe Cables For: GPU Power Supply

Jeffrey T. Jensen

We will discuss everything concerning PCIe cables in this article. The power supply unit is the most crucial component of every computer or server. It must be able to deliver consistent voltage and current following the demands of the various computer components. The power supply system uses the PCIe connections to give voltage and power to PCIe devices, including the graphics card.

Therefore, we will cover a lot of information on PCIe cables in this article. We will discuss what a PCIe cable is, the many types on the market, where and how to plug it, and other topics. Let's begin with that, then.

Table Of Contents

What Are PCIe Cables?

The PCIex16 slots supply 75 watts to the plugged-in PCI Express extension cards, typically enough to power low-demand graphics cards and other expansion cards like network and sound cards. But you'll need a PCIe cable to supply extra power if you intend to use graphics cards that consume more power, for example, the Nvidia GeForce RTX 3060 Ti.

It's important to note that only midrange to high-end graphics cards require PCIe cables to supply additional power.

Some Graphics Cards Do Not Require Power Cables (Gigabyte NVIDIA GT 710)

A PCIe cable is only sometimes used to link low-end dedicated cards.

Consider the NVIDIA GT 710 as an illustration. The main purpose of buying this virtual card was to add support for multiple monitors and enable system video output. This graphics card has a low power need because it is not intended for gaming.

This graphics card doesn’t require an extra PCIe power cable. This is because; it can draw enough power from the X16 slot it is placed in.

Some Require As Many 3 x 8 Pin Power Cables.

Compare this to the best NVIDIA GeForce RTX 3090 ASUS ROG Strix below.

Amazingly, this graphics card needs three 8-pin power cords.

The bottom line is that you must always check a new PCIe device's power needs and confirm that your PSU can deliver them whenever you purchase one, especially a graphics card.

Graphics Card Model Chip Memory CUDA Cores Frequency Interface Power Connectors
NVIDIA RTX 3080 Ti GA102 12GB GDDR6X 10242 1665 MHz PCIe 4.0 3 x 8 Pin
NVIDIA RTX 3090 GA102 24GB GDDR6X 10496 1695 MHz PCIe 4.0 3 x 8 Pin
AMD Radeon RX 6900 XT Navi 21 16GB GDDR6 5120 2015 MHz PCIe 4.0 3 x 8 Pin
NVIDIA RTX 3090 Ti GA102 24GB GDDR6X 10752 1560 MHz PCIe 4.0 3 x 8 Pin
AMD Radeon RX 6950 XT Navi 21 16GB GDDR6 5120 2100 MHz PCIe 4.0 3 x 8 Pin

How to Connect PCIe Cables to an Expansion Card

We by this time know that some PCIe gadgets require extra power and must come directly from the power source.

When using a power cable of PCIe, you run it from your power supply unit and plug it into the PCIe card to function. High-performance Graphics cards are among the components that demand it.

  1. Identify the power connectors on your graphics card. Most modern GPUs require 6-pin and/or 8-pin PCIe power connectors. The number and type needed will depend on the graphics card.
  2. Make sure your power supply has the appropriate PCIe cables. High-end power supplies often come with dedicated VGA/PCIe cables. These cables will have 6-pin and/or 8-pin connectors at the end that plug into the GPU.
  3. Connect the PCIe cables to the power supply. Make sure the cables are firmly seated in the modular power supply ports labeled VGA, PCIE or something similar.
  4. Route the PCIe cables through the case and plug them into the graphics card power connectors. The cables are keyed so they will only fit one way.
  5. For cards requiring multiple PCIe connectors, use separate power supply cables for each connector. Do not use splitter cables on high-end GPUs.
  6. Tuck away excess cable neatly using cable ties or clips so they don't obstruct airflow.
  7. Turn on the power supply and make sure the graphics card powers on. Fans should spin and lights turn on if applicable.
  8. Enjoy your new graphics capability! Monitor temperatures and power draw to make sure the card is functioning properly.

Routing Power through Power Supply Unit

PCIe power cords are included with power supply units. The PSU model determines how many PCIe wires you receive, though.

A modular power supply unit is the sort of power supply unit that is most frequently suggested for gaming and workstation systems. These have additional connectors that can add more PCIe power lines if necessary.

Let's examine a case in point. The next power supply unit is prepared for use and has two 6+2 pin power cables built in. Essentially, I can connect to a graphics card requiring two 8-pin power connectors.

I attached the 6+2 pin power cords to the graphics card which requires a 2 x 6 pin connector in the picture below.

Note that the +2 additional pin is now in the spare on both wires. It's important to note that YOUR GRAPHICS CARD's ALL POWER CONNECTORS MUST BE CONNECTED.

There were additional +2 pins which were available, so I might've plugged an extra-large graphics card to satisfy the 28-pin requirement.

Now, I may perhaps exploit the modular nature of the power source unit to connect a card that was even bigger and had a connectivity obligation of pins which are MORE than 2 x 8.

As you can see from the image above, this power supply's modular design allows for additional power outlets. Therefore, I could add extra PCIe wires to this.

However, I would be required to buy more power cables independently. In other words, whether or how many PCIe power supply cables you require will depend on your graphics card.

The manufacturer will provide this data in the form of the number of POWER CONNECTORS the graphics card has.

Additionally, ensure your PSU has appropriate PCIe connectors and a good power rating. This is so that performance won't suffer from overloading your PSU; some higher-performance cards have high power requirements.

Therefore, even if you can fulfill the power connector numbers needed, you still need a power supply unit that is the proper size.

PCIe Power Supply Cables and Basic Types

Many Power Cables of PCIe are available in the market today, and they may be identified by their PIN arrangement and power supply capability.

A) 6-Pin Power Cable

These are the smallest models on the market and have a maximum power output of 75 watts.

B) 8-Pin Power Cable

Up to 150 watts of power can be delivered over an 8-pin PCIe cable. You might be perplexed about how an 8-pin can supply twice the power of a 6-pin while using the same number of pins.

This is because not all of the cable's pins are transmitting power. Some plugs serve many purposes, including sensing, signaling, and grounding.

C) The 6+2 Pin Cable

This was evident in the earlier example. According to the connector specifications of the graphics card, a pin connector of 6 + 2, which is effectively a cable with 8-pin, can offer higher and also lower power. Consequently, you have more freedom here.

D) 12 Pin Cables

These types are the recent connectors NVIDIA has created to support its RTX 3000 line of graphics cards.

Depending on the cable gauge, a 12-pin cable may deliver power of 500–600 watts. In addition, they are now quite uncommon and are only present in very expensive systems.

E) PCIe Pigtail Cables

Pigtail connections are also available on PCIe cables. These are split into two connectors on one side and have one end attached to the supply unit of power.

An 8-pin pigtail cable is what the cable above is. Into the electrical supply unit shall go one end. Two distinct 8-pin connectors on the opposite end of the cable can be utilized with the graphics card.

The choice between separate cables and a pigtail is frequently contested. In the opinion of many die-hard fans, different cables should be the preferred option. Pigtail cables, on the other hand, have not been shown to significantly lower performance, according to others.

PCIe Cables and Graphics Card Maximum Power Consumption

The maximum power consumption of your GPU can be summarized as follows, depending on the kind and number of connectors:

PCIe x 16 (75W) 6 Pin Cable (75W) 8 Pin Cable (150W) 12Pin Cable (600W)   Max  Power Consumed
75W 0 0 0 75W
75W 1 x 75W 0 0 150W
75W 0 1 x 150W 0 225W
75W 2 x 75W 0 0 225W
75W 1 x 75W 1 x 150W 0 300W
75W 0 2 x 150W 0 375W
75W 1 x  75W 2 x 150W 0 450W
75W 0 3 x 150W 0 525W
75W 0 0 1 x 600W 675W


Frequently Asked Questions

Q. What are some common devices or components that use PCIe cables?

PCIe cables are frequently used by storage devices such as solid-state drives, sound cards, network interface cards, graphics cards, and RAID controllers, to name a few. These parts profit from the additional bandwidth PCIe cables offer since they frequently need high-speed data transfer.

Q. What are the different types of PCIe cables, and how do they differ?

PCIe cables come in several varieties: PCIe 1.0, PCIe 2.0, PCIe 3.0, and PCIe 4.0. Compared to the previous version, every new PCIe version offers more bandwidth and better performance.

Additionally, PCIe cables are available in various diameters, or "lanes," with more lanes delivering even more capacity.

Q. How do I know which PCIe cable I need for my device or component?

You must examine the documentation for the specific gadget or component or speak with the manufacturer to learn which PCIe cable you require to connect that device or component.

PCIe cables come in various shapes, widths, configurations, lane counts, and connection types; therefore, it's crucial to use the right one to prevent compatibility or performance concerns.

It's also crucial to confirm that whatever gadget or component you're connecting with a PCIe cable can receive enough power from your computer's power supply.

Final Thoughts

PCIe cables come in several forms with varying numbers of pins and voltage, and they are mostly used to supply GPUs with additional power over the maximum amount of power the PCIe x16 slot can give.

The type, quantity, and power requirements of the GPUs you want to employ in the future will determine how many PCIe cables your computer will require.

It could be a good idea to purchase a high-wattage PSU with plenty of PCIe connectors if you have a high-end graphics card so that in the future, whenever you add additional GPU, you can plug in another cable rather than having to purchase a new PSU.

In general, you should spend money on a reliable PSU that can supply the energy your GPUs require and has space for more PCIe cables in case you decide to add another GPU.

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