Computers, Laptops & Tablets Apple Troubleshooting Graphics and Display Issues on Your Mac Learn how to deal with software and hardware-related display problems By Tom Nelson Writer Tom Nelson is an engineer, programmer, network manager, and computer network and systems designer who has written for Other World Computing,and others. our editorial process Facebook Twitter Tom Nelson Updated December 06, 2019 Apple Macs iPad Tweet Share Email Watching your Mac display suddenly distort, freeze, or refuse to turn on is never a welcome event. Unlike other Mac issues, you can't delay dealing with a misbehaving display; it must be addressed immediately. If you are lucky, the glitch is just a glitch, temporary in nature and not necessarily an indication of continuing troubles to come. In many cases, display problems don't return after a restart. Lifewire / Ran Zheng Assuming the problem you're having is indeed a graphics issue and not one of the startup issues that manifest themselves as a display that's stuck on a gray screen or a blue or black screen, taking the time to run through these troubleshooting tips is a good idea. Restart Your Mac You might be surprised at how many times turning your Mac off and back on fixes issues such as display problems. Restarting your Mac puts everything back to a known state. It clears out both the system and graphics RAM, resets the graphics processing unit (GPU) and the central processing unit (CPU), and then restarts everything in orderly steps. Graphic issues can be as simple as strange colors, or shearing of objects. StockFinland/iStock Make Sure Your Mac's Display Is Plugged in and Turned On This may seem obvious, but if you're using a separate display, one not built into your Mac, you should check that it's turned on, the brightness is turned up, and that it's properly connected to your Mac. You may scoff at the idea that a cable came loose or the power somehow was turned off, but kids, adults, and pets have all been known to accidentally unplug a cable or two, push a power button, or walk across a power strip switch. If you're using a display that is an integral part of your Mac, make sure the brightness is set correctly, if you can. Reset the PRAM/NVRAM The parameter RAM (PRAM) or non-volatile RAM (NVRAM) contains the display settings your monitor uses, including resolution, color depth, refresh rate, number of displays, color profile to use, and more. If the PRAM in older Macs or the NVRAM in newer ones should become corrupt, it can change the display settings, causing problems that include strange colors and refusing to turn on. Use our guide for how to reset your Mac's PRAM (Parameter RAM) or NVRAM to reset the PRAM or NVRAM. Reset the SMC The System Management Controller (SMC) also plays a role in managing your Mac's display. The SMC controls a built-in display's backlighting, detects ambient lighting, and adjusts brightness, controls sleep modes, detects the lid position of Mac laptops, and a few other conditions that can affect a Mac display. Reset using the guide: Resetting the SMC (System Management Controller) on Your Mac Safe Mode Use Safe Mode to isolate graphics issues you may be having. In Safe Mode, your Mac boots into a stripped-down version of the Mac OS that only loads the bare minimum of extensions, disables most fonts, clears out many of the system caches, keeps all startup items for starting, and deletes the dynamic loader cache, which is a known culprit in some display problems. Before testing in Safe Mode, disconnect all external peripherals connected to your Mac, except for the keyboard, mouse or trackpad, and the display. Start the Mac in Safe Mode following the guide: How to Use Your Mac's Safe Boot Option. After your Mac restarts in Safe Mode, check to see if any of the graphics anomalies are still occurring. If you're still experiencing the problems, you have a possible hardware issue. Jump ahead to the Hardware Issues section. Software Issues If the graphics problems appear to be gone, then your problem is likely software-related. Check any new software you've added, including Mac OS software updates, to see if they have any known issues with your Mac model or with software you're using. Most software manufacturers have support sites you can check. Apple has both a support site and support forums where you can see if other Mac users are reporting similar issues. If you don’t find any help through the various software support services, try diagnosing the issue yourself. Restart your Mac in normal mode, and then run your Mac with only basic apps, such as email and a web browser. If all works well, add any apps you use that may have helped cause the graphics issue one at a time. Continue until you're able to repeat the problem, which narrows down the software cause. However, if you still have graphics issues without opening any apps, and the graphics issues were gone when running in Safe Mode, try removing startup items from your user account, or create a new user account for testing. Hardware Issues If it looks like the problem is hardware-related, run the Apple Diagnostics to test your Mac's hardware for any issues. You can find instructions at: Using Apple Diagnostics to Troubleshoot Your Mac's Hardware. Apple has occasionally extended repair programs for specific Mac models. This usually happens when a manufacturing defect is discovered. Check to see if your Mac is included in those that have an acknowledged defect. Apple lists active exchange or repair programs at the bottom of the Mac Support page. Apple offers hands-on hardware support through its Apple Stores. You can make an appointment to have an Apple tech diagnose your Mac's problem, and if you wish, repair your Mac. There is no charge for the diagnostic service, but you need to bring your Mac to the Apple Store.