Lenovo T420

[donbrew]

Lenovo T420 bought from OpenBox, I suspect factory reject, random crashes with various stopcodes in Windows 7 & Windows 10 & Ubuntu. Ubuntu just freezes. Windows reboots. Oddly, MemTest86 runs fine for hours.

Updated UEFI bios.

MemTest86 7.5 and 8.0 and Memtest86+ 5.01

Passes all test except Bit Fade with upwards of 279 errors. Even with the addon memory module removed. It seems the first 4 GB are on the MB.

Does this mean there is a fatal hardware problem? Should I continue troubleshooting?

[David (PassMark)]

> Oddly, MemTest86 runs fine for hours


If by "fine" you mean "catastrophically bad", then yes it runs fine. 279 errors isn't fine.

I am not sure how much control you have in the Lenovo UEFI BIOS, but maybe you can increase the refresh rate for the RAM. Might help if all the errors are bit fade.

[donbrew]

Strange thing: I found out where the other stick was hidden; R&Rd it, then removed the other stick rerun memtest+ got all errors on the fade test, but the laptop runs just fine now without the extra 4 GB.

Even tried switching the sticks and using only one at a time. Evidently there is a defect in the one that only shows up in the fade; maybe that explains why Ubuntu would not exit right.

Maybe I don't understand the display on that test. I turned it off after 3 megs.