There was a time when no PC could play a decent game unless it was outfitted with a discrete graphics processor. Today, most off-the-shelf desktop rigs — and nearly all notebook PCs — rely entirely on the CPU for video and graphics processing. And yet the market for discrete graphics continues to thrive. If you don't give a flying joystick about playing AAA PC games, is a video card a worthwhile upgrade? Let's compare the performance of integrated and discrete graphics processors to find out.
AMD and Intel have significantly improved the graphics technologies integrated into their respective CPUs. AMD's Kaveri-class Accelerated Processing Units (APUs) incorporate the same powerful Graphics Core Next (GCN) architecture of its best discrete Radeon-series graphic processors.
Intel has likewise updated the features and capabilities of its HD-series graphics engines, which are integrated into its fourth-generation Core processors (codenamed Haswell). They now deliver broader support of Microsoft's DirectX 11.1 API (an application program interface originally developed for Windows games), they can easily support multiple displays (as well as 4K models), and they're compatible with many more games.
To determine the difference discrete graphics could make, we assembled two computers. One is powered by an AMD A8-7800 (a Kaveri-class APU with an integrated Radeon R7-series graphics processor), and the other has an Intel Core i7-4670 (a Haswell-class CPU with an integrated Intel HD 4600 graphics processor). We then ran a series of benchmarks with and without a discrete video card onboard each system. You might be surprised by the results.
The argument for discrete graphics
Champions for discrete graphics usually tout one major benefit: performance. All but the lowest-end video card will have a far more powerful GPU than what you'll find inside a CPU. What's more, the card will provide its GPU with a dedicated pool of high-speed memory. An integrated GPU, in contrast, must share both system memory and the data bus. You can usually crank up a game's visual quality settings with a discrete GPU, and it will still run circles around integrated graphics.
There are other benefits to using discrete graphics cards, too. With Nvidia's current-gen graphics cards, for example, users can take advantage of proprietary features such as ShadowPlay and PhysX. ShadowPlay leverages the video-encoding engines built into Nvidia's GPUs to record and stream live gameplay videos in real time, with negligible impact on frame rates. It's a key feature for Nvidia's Shield handheld gaming device.
PhysX is Nvidia's proprietary physics-simulation technology, which can make the objects in games behave more like they would in the real world (cloth ripples and tears, liquids flow and splatter, buildings explode into small shards, and more). PhysX isn't universally supported, but it can have tremendous visual impact in games where it is.
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