MemTest64 vs MemTest86

MemTest64 is a free, standalone Windows utility for checking system memory for hardware-level problems. It runs inside Windows with a graphical interface, loading physical memory with test patterns and applying detection algorithms that identify errors automatically. You choose how much memory to test, which can limit the effect on other work. The utility runs without a reboot or DOS mode, does not require administrator privileges, needs no installation, and makes no registry changes. Listed processor support includes modern Intel Core and AMD Ryzen systems. Supported systems are 64-bit Windows XP, Vista, 7, 8, 10, and 11. TechPowerUp describes it as useful to overclockers adjusting memory timings and DRAM speeds. The utilities listing identifies version 1.0, dated April 20, 2017, and the product page links to a support forum.

MemTest86 is a bootable utility that checks computer RAM for faults using memory test algorithms and patterns. It runs from a USB drive without an installed operating system, although Windows, Linux, or an Intel-based Mac can be used to create that drive. Version 11.7 requires UEFI firmware and x86 or ARM64 hardware, and does not support Apple Silicon M-series Macs. Its listed coverage includes 14 algorithms, such as SIMD, Row Hammer, and DMA tests, and support for DDR2, DDR3, LPDDR4, LPDDR5(x), ECC, CDIMM, and CAMM2 memory. It can create customizable HTML reports and, on supported configurations, decode an error address to identify a failed DIMM or chip. The Free Edition supports up to 16 CPU cores; Pro supports up to 512 and adds automation and custom tests. Site Edition adds PXE-based LAN deployment and Management Console integration. The Free Edition costs nothing; Pro Download costs $116, paid once.