[xubuntu-users] troubleshoot mcelog Machine Check Exception messages

[scar]

hi i have a computer that has been hard rebooting over and over... i
thought it was a kernel/software problem as the machine froze while
installing a kernel update.  i took the opportunity to wipe it clean and
install xubuntu on it.  the installation went well and i was able to
restore my backup, but now the machine is freezing again during boot-up.
 this time, however, it is not rebooting automatically and has provided
a Machine Check Exception output, which i ran through mcelog on my laptop:

$ sudo mcelog --ascii
CPU 0: Machine Check Exception: 4 Bank 4: b200001000010c0f
CPU 0: Machine Check Exception: 4 Bank 4: b200001000010c0f
TSC 1295c993c5
TSC 1295c993c5
PROCESSOR 2:40ff2 TIME 1414042838 SOCKET 0 APIC 0 microcode 0
Hardware event. This is not a software error.
CPU 0 BANK 4 TSC 1295c993c5
TIME 1414042838 Wed Oct 22 22:40:38 2014
STATUS b200001000010c0f MCGSTATUS 4
CPUID Vendor AMD Family 15 Model 79
PROCESSOR 2:40ff2 TIME 1414042838 SOCKET 0 APIC 0 microcode 0
$

i had to type in the 3 lines manually and then mcelog produced the
output starting with "Hardware event...." (it echoed the first two lines
after i typed them in).  so i'm trying to nail down what hardware is
faulty so i can fix it.  all i've been able to find out there is
'contact your hardware vendor'... so is that my motherboard
manufacturer?  or the CPU manufacturer?  or what?

i did run memtest overnight for 12 hours, 13+ passes and no errors, so
it seems the RAM is OK....