Software for testing memory?

[NeoPTLD]

I've always used Memtest86.

There are Memtest86+ and Windows Memory Test available as well. The Windows Memory Test, despite the name boots from CD-ROM and has a very similar user interface as Memtest86.

Which one should I use and why?

 

[BenchZowner]

Memtest86+ because it's more 'updated'.
But then, especially when testing 4GB configurations after successfully running memtest/memtest86+ I'd recommend looping 3D Mark06 15 times to check if it's 3D Stable ( 4 DIMMs or 4GB Kits put a lot of stress on the MCH and sometimes won't be 3D Stable even when passing memtest flawlessly [ memtest doesn't stress the MCH as much as windows 3d apps ] )