MultiBoot USB
This is a project that contains a collection of GRUB files and scripts that will allow you to create a pendrive capable of booting different ISO files.
Memtest86 and Memtest86+ are memory test software programs designed to test and stress test an x86 architecture computer’s random access memory (RAM) for errors, by writing a series of test patterns to most memory addresses, then reading back the data written, and comparing for errors. Each tries to verify that the RAM will accept and correctly retain arbitrary patterns of data written to it, that there are no errors where different bits of memory interact, and that there are no conflicts between memory addresses.