You can use the Apple Hardware Test (AHT) to help diagnose problems with your Mac's hardware. This can include issues with a Mac's display, graphics, processor, memory, and storage. You can use the Apple Hardware Test to rule out most hardware issues when troubleshooting your Mac.
How to Use Apple Diagnostics on Your Mac to Find Hardware Problems
True hardware failure is rare, but it does happen. One common hardware failure is with random access memory (RAM). Apple Hardware Test can check your Mac’s RAM and let you know if there are any problems. Some Mac models let you upgrade the RAM yourself, but in general, the newer your Mac, the less likely it is to support this feature.
Not all Macs can use the web-based AHT. Some must use a local version that is either installed on the Mac's startup disk or included on the OS X install DVD.
Macs made after 2013 must use a newer version of the hardware test called Apple Diagnostics. For instructions on testing newer Macs with Apple Diagnostics, see Using Apple Diagnostics to Troubleshoot Your Mac's Hardware.
