Microsoft Introduces CASO Technology That Lets Hybrid Laptops Switch Between iGPU & dGPU More Efficiently

Microsoft’s Cross Adapter Scan-Out (CASO) technology, introduced in 2021, was conceptualized as a salient solution for platforms wielding both discrete and integrated graphics. This pioneering approach facilitates seamless switching between GPUs from leading vendors—NVIDIA, AMD, and Intel—on laptop platforms, eliminating the necessity for a MUX multiplexer chip. Initially, it exclusively championed DX11, but recent advancements, commencing earlier this year, have ushered in DX12 support. Microsoft has recently disseminated an intricate exposition on the CASO technique via their DirectX blog.

Modern laptops are indeed furnished with inherent mechanisms to orchestrate the judicious interchange between discrete and integrated graphics: the integrated graphics shoulder lightweight tasks, while their discrete counterparts grapple with the more labor-intensive chores such as gaming or intricate rendering. To illustrate, NVIDIA boasts its Advanced Optimus, while AMD parades its Smart Access Graphics. However, both these blueprints hinge upon the MUX chip and are proprietary in nature, potentially rendering them incompatible with hardware from alternative manufacturers.

MUX chips, while a frequent sight on gaming-oriented laptops, are conspicuously absent in many of their sleeker counterparts. In a typical scenario, once a game is rendered via discrete graphics, it is initially transcribed onto a shared resource, and subsequently from this shared pool onto the integrated graphics for output. A cursory perusal of this procedure divulges its inefficacy, invariably culminating in heightened latency and a perceptible dent in the game’s FPS. The sole merit, it seems, is a modus operandi allowing for harmonious collaboration between discrete and integrated graphics without demanding auxiliary hardware.

CASO’s inception by Microsoft aims to emancipate laptops from the clutches of the MUX chip, streamlining the aforementioned transfer process. It empowers discrete graphics to render images that require just a solitary copy for display output, culminating in superior performance, diminished display latency, and augmented battery longevity. According to Microsoft’s internal assessments, the activation of CASO has bolstered average game FPS by a commendable 16% and pared down display latency by 27%. Additionally, Windows TDR (Timeout Detection and Recovery) events have witnessed a reduction of 45%.

Presently, CASO has been seamlessly integrated into Microsoft Windows 11 and is, by default, activated on compatible devices. For CASO’s activation, the prerequisites are either an AMD Ryzen 6000 processor or a processor fortified with Intel Iris Xe integrated graphics that supports WDDM 3.0 or its superior iterations. It is worth noting that graphics drivers from the industry stalwarts—NVIDIA, AMD, and Intel—have all pledged allegiance to the CASO technology.