While many people pay attention to the speed of their computer’s CPU (central processing unit) and how much RAM (random-access memory) their applications need, the video card (also called the graphics card) is getting more attention as image-editing, video-editing, and game applications increasingly rely on it. In addition, today’s desktop monitors are larger than ever, and a new wave of high resolution monitors such as the Apple Retina display have a dramatically increased pixel density (pixels per inch resolution) that has also increased the number of screen pixels that need to be managed for a given screen size. All of these changes add to the work that a video card has to do.
But how do you know if your current video card has enough memory? This article covers:
- Why is video RAM important?
- How can you measure video RAM usage on a Mac?
- Can you add more VRAM to a Mac?
- How do you know how much VRAM is available for Macs with integrated graphics?
- Is your Mac video hardware good enough for Adobe software? (with links to Adobe GPU FAQs)
- Can I upgrade my Mac graphics capability with an external GPU?
I have updated this article since it was first written.
Why is video RAM important?
In the same way that a computer has a CPU (central processing unit) that interacts with RAM, a video card has a GPU (graphics processing unit) that works with VRAM (video random-access memory). The primary mission of the video card is to drive your displays and make graphics show up faster on those displays.
On low-end computers, the GPU is often on the same chipset as the CPU; this is called integrated graphics or integrated video. Any memory needed for graphics is taken from the main system RAM (see details about VRAM amounts on Macs with integrated video). On high-end computers the CPU and GPU are separate chipsets, each with their own memory; this is called discrete graphics or dedicated graphics. This design allows more powerful GPUs to be used, and with more VRAM. In a desktop computer, the GPU and VRAM are often on a completely separate card that can be easily replaced.
Today’s video cards are so powerful that many applications now use the GPU to get through photo and video processing and effects faster, which also frees up the CPU to process other things at the same time. The power of the GPU has helped make it possible for affordable computers to smoothly edit HD video, high-resolution stills, and 3D graphics and animation. For these reasons, you see video card specs creeping into the system requirements of more software such as Adobe Photoshop CS6, Adobe Bridge, and Adobe Premiere Pro. Photoshop CS6 requires 256MB of video RAM and prefers at least 512MB. Earlier versions of Photoshop limited GPU acceleration to document navigation (such as smoothly panning and zooming very large documents) and 3D, but Photoshop CS6 now uses the GPU to speed up additional features such as Liquify.
How can you measure video RAM usage on a Mac?
Many Mac users know that you can monitor a lot of system information using the Activity Monitor utility, and that the System Information utility can tell you which graphics card is inside your Mac. However, one statistic you can’t get out of either utility is the current memory usage of the video card. For that, you need to turn to non-Apple utilities.
Starting with iStat Menus 3.1.6, you can see the memory usage of the video card in the menu for the CPU stats. You’ll find this in the GPU section, which is most of the way down the menu. It has a bar graph of the amount of VRAM being used and it names the graphics in use. For example, my MacBook Pro has both Intel HD Graphics 3000 (integrated with the CPU) and an AMD Radeon HD 6750M (discrete GPU), and in the figure below you can see that the discrete Radeon is currently active because at least one running application, such as Photoshop, caused discrete graphics to activate.
iStat Menus is USD$16, so if you don’t want to pay that much take a look at the next option…
A free alternative to iStat Menus is atMonitor. It doesn’t display GPU information in the menu bar; only in a floating palette. You can optionally make the palette stay on top of all other applications, but that means it will permanently occupy part of your screen instead of staying out of the way on the menu bar. Still…it’s free. And it displays not only the VRAM in use, but GPU activity too. (Users on OS X 10.8 Mountain Lion or later: According to the atMonitor FAQ, “To make atMonitor compatible with MacOS 10.8 we have removed all GPU related features.” The atMonitor home page says “The last version of atMonitor to support GPU related features is atMonitor 2.7.1.”) [Update, July 2014: The atMonitor site appears to be offline, I don’t know why.]
But what does it all mean?
You can watch a graphics card utility such as iStat Menus or atMonitor as you use different applications or change your monitor settings. If the amount of VRAM in use is always well below 100% then your current video card is fine. But if the VRAM usage is consistently near 100%, your Mac might run Photoshop CS6 and professional imaging applications faster if you switch to a video card with more VRAM.
Some of the general factors that can increase VRAM usage are:
- Larger displays and multiple displays. It takes more graphics card memory to display more pixels. Connecting an external monitor will use more VRAM because you increase the number of pixels to update. I believe that adding Spaces (OS X virtual desktops) has a similar effect on VRAM as adding displays.
- Higher pixel density. Retina/HiDPI displays, including 4K/5K desktop displays, pack many more pixels into each square inch than a traditional display. That increased pixel density requires more VRAM.
- Larger documents and multiple documents. The more graphics documents you have open, the more video RAM it takes to manipulate them.
- 3D. Applications with 3D features commonly have them handled by the GPU and its VRAM. For example, if you use the 3D features in Photoshop or Adobe After Effects, the VRAM and 3D capabilities of your card matter more than if you only edit 2D images.
- GPU-accelerated features. Certain features use the GPU to perform dramatically faster, such as Liquify in Photoshop CS6 or the Mercury Graphics Engine in Adobe Premiere Pro CS6. Features like these often need a specific GPU and a minimum amount of VRAM to achieve the speed boost, so double-check their graphics card requirements to make sure that the card in your computer qualifies.
Given those general guidelines, keep in mind that it’s possible for two Macs with the same specifications to have very different VRAM usage patterns if different features, document sizes, and display resolutions are used. Also, some recent MacBook Pros have two sets of graphics hardware that they automatically switch between: integrated graphics (the GPU is part of the CPU) for optimal battery life, and a dedicated video card with its own additional VRAM that kicks in when a specific application needs high-performance graphics.
If you know of any other Mac utilities that help monitor the graphics card, or if you want to suggest similar utilities for Windows, say so in the comments!
Can you add more VRAM to a Mac?
The ability to increase the VRAM in your Mac depends on whether it has discrete graphics or integrated graphics.
On Macs with discrete graphics, the only model that makes it possible to upgrade the amount of discrete VRAM is the aluminum Mac Pro tower desktop. In that type of Mac the video card is in a standard expansion slot so it can be easily replaced with a better one. In OS X 10.8.3 or later you can use a wide range of PC graphics cards in an aluminum Mac Pro; it used to be that you could only use graphics cards specifically flashed for Macs. One place to find a wide range of Mac Pro-compatible graphics cards is the online store macvidcards.com (that’s just a suggestion, as I have no experience or connection with that store).
Unfortunately, the graphics hardware in all other Macs—desktops and laptops—can’t be upgraded, either because they have graphics cards permanently soldered to the motherboard or because the graphics are completely integrated with the CPU, which also can’t be replaced. The graphics cards in the 2013 Mac Pro (the black cylinder) appear to be removable, but a better graphics card is not yet available for it.
On Macs with integrated graphics, because graphics hardware uses the same RAM as the system it may be possible to increase VRAM by adding more system RAM. But how it works depends on which Mac you have and which version of OS X it’s running, and to learn about that you want to read the next section.
How do you know how much VRAM is available for Macs with integrated graphics?
(I added this info in June 2013) When a computer has discrete graphics, the amount of VRAM it has is fixed and usually clearly stated. When a computer has integrated graphics it’s harder to tell how much VRAM it can use, partly because the graphics hardware doesn’t have its own memory. In addition, in some systems the amount of VRAM used by integrated graphics varies depending on how much RAM is installed. This has made the amount of VRAM in Macs with integrated video a bit of a mystery when you’re trying to figure out if you can run specific software that requires a minimum amount of VRAM. Now Apple has published a tech note detailing how much system RAM is allocated to VRAM for specific Mac models that have integrated video, and here is the link to that:
That tech note contains several important lessons. First, for some Macs with integrated graphics, the only way to maximize the amount of VRAM is to upgrade the amount of system RAM. Note that in some models, VRAM will increase only up to an amount of RAM that’s lower than the maximum that Mac can take; beyond that point adding more RAM doesn’t increase VRAM any further.
Apple’s tech note also shows that that Macs with both integrated and discrete graphics hardware may have a lower VRAM amount available when using integrated graphics than Macs that have integrated graphics only. My take is that this is not a disadvantage at all, because on Macs with dual graphics hardware, OS X probably figures that if your graphics needs are getting that serious it might as well switch over to the faster discrete graphics processor that also has its own VRAM. Being able to use the VRAM of the discrete graphics hardware lets OS X release the RAM that was being used as VRAM, so more RAM becomes available to you.
The end of the Apple tech note also describes the graphics performance benefits of making sure you install matched pairs of RAM modules.
[Note (October 22, 2013): OS X 10.9 Mavericks improves how Macs work with integrated graphics. It can dynamically adjust the amount of RAM allocated to VRAM to respond to changing application requirements, including the ability to release VRAM back to RAM when it isn’t needed for graphics. Also, you no longer necessarily need discrete graphics hardware to use OpenCL graphics acceleration, because Mavericks can run OpenCL on Intel HD Graphics 4000 or better. (Some applications may have more stringent requirements; for example, Adobe Premiere Pro CC 2014 requires Intel Iris graphics or better for OpenCL acceleration on integrated graphics.) For more details about all of these improvements, read the excellent article OS X 10.9 Mavericks: The Ars Technica Review by John Siracusa.
Is your Mac video hardware good enough for Adobe software?
Adobe has been increasing its use of graphics hardware to help accelerate its software. Here are links to graphics requirements for some Adobe applications:
- Adobe Photoshop CC and CC 2014 GPU FAQ
- Adobe Photoshop CS6 GPU FAQ
- Adobe Camera Raw 9 GPU FAQ
- Adobe Lightroom 6/CC GPU FAQ
- Adobe Premiere Pro system requirements (with list of video cards supported for GPU acceleration)
- GPU (CUDA, OpenGL) features in After Effects CS6 and CC
- Enabling CUDA for Premiere Pro and After Effects in the MacBook Pro Retina
[October 26, 2012 Photoshop CS6 update: If you use 3D features and are a Creative Cloud member, those features will require 512MB of VRAM on the graphics card in future versions of Photoshop. For details, see: Heads Up: Photoshop System Requirement Changes]
If you’re trying to decide on graphics options for your Mac, keep in mind that you don’t necessarily need expensive high-end graphics. For photography and design in Adobe applications, the amount of video RAM is more important than the sheer power of the video card, and much less graphics power is needed than for serious gaming. But the more you edit video or use 3D, the more you may need a video card with additional processing power. Note that Adobe Photoshop Lightroom CC/6 uses GPU acceleration for the Develop module only, where in my experience it makes a big difference, but for now the rest of Lightroom is more CPU-based.
In older versions of Adobe software, GPU acceleration largely focused on the CUDA technology in NVIDIA graphics hardware. Recent versions of most GPU-accelerated Adobe applications support OpenCL technology, which has vastly expanded the range of supported graphics hardware that Adobe software can use for GPU acceleration.
One nice side effect of Adobe adding OpenCL support is that in many cases GPU acceleration no longer requires discrete graphics. The Intel Iris and Iris Pro integrated graphics now found in much of the Mac product line now qualifies for GPU acceleration in many applications including Adobe Premiere Pro. If you are a serious video professional NVIDIA CUDA acceleration still provides a bigger boost than OpenCL, especially for 3D work in Adobe After Effects. Adobe has also been improving its support of the AMD FirePro graphics cards available for the 2013 Mac Pro (the black cylinder).
Can I upgrade my Mac with an external GPU?
[Added April 2017] With the high bandwidth available through Thunderbolt 3, it’s become possible to create a graphics upgrade solution involving a desktop-class video card in an external chassis connected to a PC or Mac with a Thunderbolt cable. Many Mac users wonder whether it’s possible to upgrade their Mac’s graphics capabilities this way.
Technically, it is possible. Practically, it’s not that simple.
The Mac system does not officially support external GPU solutions, so current solutions tend to require driver software that works around Mac system limitations and security. This also means the driver software is at risk of breaking when Apple updates macOS.
The cost of currently available solutions is not that cheap after you factor in the cost of the chassis hardware and the video card you want to put into it.
The promise of external GPUs appeals very much to owners of older Macs. However, those are the Macs least able to use an external GPU. Graphics processors move so much data that external GPUs are really built for Thunderbolt 3 bandwidth, especially when driving 4K+ displays. Older Macs only have Thunderbolt 1 or 2, which may not be able to move the required amount of data fast enough. A GPU only helps if the time needed to get the data out to the GPU and back, plus processing time, is less than the time it would have taken to process the data without the GPU. There are some external GPU systems that advertise compatibility with older Macs going back a few years, but their performance won’t be as high as on Macs with Thunderbolt 3.
AppleInsider has a good article about Mac external GPUs: Thunderbolt 3-Equipped MacBook Pro Can Use External GPUs, But At a Cost. While they do document some impressive performance gains, some of the subheadings in the article are “The literal price you pay is steep,” “The procedure is not for the timid,” and “Yet more potential pitfalls await!”
So practically, it’s best for most Mac users to wait until simpler and less expensive solutions are available—especially if Apple provides an approved path to external GPUs in a future version of macOS. For now, you can keep track of how well the current solutions work by monitoring Mac enthusiast web sites. One site is long-time Mac performance test site Bare Feats, which has tested a number of external GPUs lately.