My computer is very old, and uses DDR2, with a max of 8 Gigs of RAM. I recently replaced the two RAM cartridges in my computer with enough RAM to max it out. But, just a while ago, I tried to run a Memtest, and it froze before it even finished 1% of the first pass. The RAM has been functioning fine on the regular computer, and is detected by the Memtest, but it just won't progress, and I have to turn it off and on again to exit the Memtest (esc doesn't work). Does anybody know what's going on?
SnapOverflow
While hardware fault and memtest bugs are possible, there's also LP #1876157: Memtest86+ in Ubuntu 20.04 doesn't work. So if the memtest you ran was from Ubuntu 20.04 images, try running memtest from Ubuntu 18.04 images.
According to https://www.memtest86.com/tech_freezing-lockups.html
If the freeze occurs in MemTest86 but the system runs normally otherwise, the problem is likely with the UEFI firmware. The most common issue is when running MemTest86 using multiple CPU cores (default behaviour). There is a forum post that tracks known motherboard/BIOSes with problems running using multiple CPU cores. If you believe this issue is related to the UEFI BIOS, please send a copy of the debug log to PassMark Software. This type of bug tends to be very repeatable (not random)
Another BIOS bug we have seen is some old Dell machines have a 32bit addressing bug that prevents testing more than 4GB of RAM. In this case testing will freeze early on during Test 0 (the address test), while test in the 0x100000000 (4GB) memory range. To partially work around this issue you can limit the maximum address to test to below 0x100000000. This might mean a lot of RAM doesn’t get tested however. Or contact the motherboard vendor and ask for updated BIOS.