Never waste time. Boot MemTest86 from a USB drive and let it run overnight. One pass is insufficient. Eight passes is standard. Twenty-four passes is conclusive.
It functions identically in practice—pre-OS, pattern-based exhaustive testing. Apple does not offer a third-party memory tester because Macs have integrated hardware diagnostics. memory diagnostic tool
MemTest86 boots from a USB drive (it does not run inside Windows). This allows it to test all of your memory, including areas that the OS reserves for itself. Never waste time