Just a quick note related to my old memory-testing related post: memtest86+ now runs on Intel Macs just fine. Just download the pre-compiled bootable ISO file, use Disk Utility to create a CD out of it, and boot from it. This is much better than the previous solution where you had to boot Mac OS X in single-user mode, because memtest86+ won’t need Mac OS X (or any other OS) to run, which means it uses a very, very small memory footprint. The least memory you’re using, the more memory memtest will be able to test. This version of memtest uses a few KB of RAM. Booting Mac OS X, even in single user mode, will use at least 50 MB. It’s a really huge difference. And being able to boot directly from a CD is pretty handy.