GPU switching is a mechanism used on computers with multiple graphic controllers. This mechanism allows the user to either maximize the graphic performance or prolong battery life by switching between the graphic cards. It is mostly used on gaming laptops which usually have anintegrated graphic device and adiscrete video card.

Most computers using this feature contain integrated graphics processors and dedicated graphics cards that applies to the following categories.

Also known as:Integrated graphics,shared graphics solutions,integrated graphics processors (IGP) orunified memory architecture (UMA). This kind of graphics processors usually have much fewer processing units and share the same memory with theCPU.

Sometimes the graphics processors are integrated onto a motherboard. It is commonly known as:on-board graphics. A motherboard with on-board graphics processors doesn't require a discrete graphics card or aCPU with graphics processors to operate.

Also known as:discrete graphics cards. Unlike integrated graphics, dedicated graphics cards have much more processing units and have its ownRAM with much higher memory bandwidth.

In some cases, a dedicated graphics chip can be integrated onto themotherboards, B150-GP104 for example. Regardless of the fact that the graphics chip is integrated, it is still counted as a dedicated graphics cards system because the graphics chip is integrated with its own memory.

MostPersonal Computers have a motherboard that uses aSouthbridge andNorthbridge structure.

TheNorthbridge is one of the core logicchipset that handles communications between theCPU,GPU,RAM and theSouthbridge. The discrete graphics card is usually installed onto the graphics card slot such asPCI-Express and the integrated graphics is integrated onto the CPU itself or occasionally onto the Northbridge.^{[citation needed]} The Northbridge is the most responsible for switching between GPUs. The way how it works usually has the following process (refer to the Figure 1. on the right):^[1][2]

1. The Northbridge receives input from Southbridge through theinternal bus.
2. The Northbridge signals to CPU through the Front-side bus.
3. The CPU runs the task assignment application (usually the graphics card driver) to determine which GPU core to use.
4. The CPU passes down the command to the Northbridge.
5. The Northbridge passes down the command to the according GPU core.
6. The GPU core processes the command and returns the rendered data back to the Northbridge.
7. The Northbridge sends the rendered data back to Southbridge.

The Southbridge is a set of integrated circuits such Intel'sI/O Controller Hub (ICH). It handles all of a computer's I/O functions, such as receiving the keyboard input and outputting the data onto the screen. The way how it usually works usually has two steps:^[3]

1. Take in the user input and pass it down to the Northbridge.
2. (Optional) Receive the rendered data from the Northbridge and output it.

The reason why the second step can be optional is that sometimes the rendered the data is outputted directly from the discrete graphics card which is located on the graphics card slot so there is no need to output the data through the Southbridge.

GPU switching is mostly used for saving energy by switching between graphic cards. The dedicated graphics cards consume much more power than integrated graphics but also provides higher 3D performances, which is needed for a better gaming and CAD experience. Following is a list of theTDPs of the most popular CPU with integrated graphics and dedicated graphics cards.

The dedicated graphics cards exhibit much higher power consumption than the integrated graphics on both platforms. Disabling them when no heavy graphics processing is needed can significantly lower the power consumption.

Nvidia Optimus™ is a computer GPU switching technology created byNvidia that can dynamically and seamlessly switch between two graphic cards based on running programs.

AMD Enduro™ is a collective brand developed by AMD that features many new technologies that can significantly save power. It was previously named as:PowerXpress andDynamic Switchable Graphics (DSG). This technology implements a sophisticated system to predict the potential usage need for graphics cards and switch between graphics cards based on predicted need. This technology also introduces a new power control plan that allows the discrete graphics cards consume no energy when idling.^[8]

In personal computers, theIGP (integrated graphics processors) are mostly manufactured byIntel andAMD and are integrated onto theirCPUs. They are commonly known as:^[9][10]

• Intel HD and Iris Graphics - also calledHD series andIris series
• AMD Accelerated Processing Unit (APU) - also formerly known as:fusion

The most popular dedicated graphics cards are manufactured byAMD andNvidia. They are commonly known as:

• AMD Radeon
• Nvidia GeForce

Most commonoperating systems have built-in support for this feature. However, the users may download the updated drivers fromNvidia orAMD for better experience.

Windows 7 has built-in support for this feature. The system automatically switches between GPUs depending on the program that's running. However, the user may switch the GPUs manually through device manager or power manager.^[11]

Modern Linux systems handle hybrid graphics in two parts: power/control for the inactive GPU, and optional render offloading for individual applications.

• vga_switcheroo (in the kernel since 2.6.34) coordinates power and mux control on systems with multiple GPUs. It was designed primarily for muxed designs (hardware display switch), and on muxless laptops it is typically used only for power control. A display server restart is no longer required for offloading on muxless systems.^[12]

• DRI PRIME (Mesa) enables per-process render offload on muxless systems: an app renders on the discrete GPU and the integrated GPU presents the result. Users can opt in via theDRI_PRIME environment variable (e.g.,DRI_PRIME=1) or desktop integration.^[13]

• On GNOME, theswitcheroo-control service exposes the discrete GPU to the shell, adding a “Launch using Discrete Graphics Card” entry to app menus on supported systems (Wayland or Xorg), which invokes render offload under the hood.^[14]

• With the proprietary Nvidia driver, render offload is provided asPRIME Render Offload (supported since driver 435.xx). Distributions commonly ship a helper likeprime-run or desktop menu entries that set the required environment for offloading.^[15]

• On muxless systems the internal display is hard-wired to the integrated GPU; the discrete GPU cannot directly drive that panel and instead renders offscreen for composition by the iGPU. External displays connected to the dGPU may allow direct output depending on the laptop’s wiring.^[15]
• Power-saving behavior varies by driver and distro defaults. Some setups need explicit configuration to power down the inactive GPU when idle.^[12]
• Desktop integrations (e.g., GNOME's menu item) simply opt an app into offload; they do not "auto-switch" the whole session. Users can still launch apps on either GPU as needed.^[14]

• Graphics processing unit (GPU)
• Nvidia Optimus
• ATI Hybrid Graphics

• AMD official website
• Nvidia official website
• Intel official website
• Notebook Check official website

• Computer hardware

• Articles with short description
• Short description is different from Wikidata
• All articles with unsourced statements
• Articles with unsourced statements from July 2020