MCE Errors

Myu · Posted: Thu Nov 02, 2017 5:10 pm Post subject: MCE Errors

Hello everyone,

I got a log of "MCE Errors" thrown at me at boot and on all TTY since a day, I installed app-admin/mcelog and added CONFIG_X86_MCELOG_LEGACY=y to my kernel to be able to look at them at ease and it doesn't look good :

eccerr0r · Posted: Thu Nov 02, 2017 5:20 pm Post subject:

Yes, usually it's a bad sign if it had been working before.

If it has always been doing MCE errors, you should look into new BIOS, trying another kernel (or another distribution) (mostly to rule out kernel config issues).

If it just started doing it with a known stable configuration, check fan for cleanliness and heatsink/compound, stop overclocking or underclock it, else you may well be looking into hardware replacements (motherboard, CPU, possibly PSU).
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Intel Core i7 2700K/Radeon R7 250/24GB DDR3/256GB SSD
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Myu · Posted: Thu Nov 02, 2017 5:39 pm Post subject:

Thanks for the reply eccerr0r (username almost checks out ! :mrgreen:

)

It never did that kind of errors before, the thing is sometimes it boots with the errors, sometimes not even with no hardware change in between...

Indeed some other post suggested various overheating issues or bad PSU, I cleared the dust and put another fan to work, recheck all connections, the errors are still there but seems my system can run (at least for what I tried so far : light browsing)

I'll look into underclocking and yes, maybe it's time to keep an eye on thrift store deals.
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Gentoo stable with bits of ~amd64 // Xfce 4.13 + Compiz Reloaded.

Myu · Posted: Thu Nov 02, 2017 5:52 pm Post subject:

Damn it's pretty crazy, htop & cat /proc/cpuinfo were showing 3 cores then 2 then one... instead of 4 (i5-3470)

Edit : Ok, mcelog is disabling CPU cores due to L2 cache errors... makes sense.
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Gentoo stable with bits of ~amd64 // Xfce 4.13 + Compiz Reloaded.

eccerr0r · Posted: Thu Nov 02, 2017 10:37 pm Post subject:

I'd look into M/B or PSU issues and not the CPU if more than one core is failing... though it's still possible for a CPU failure, it's not likely.
_________________
Intel Core i7 2700K/Radeon R7 250/24GB DDR3/256GB SSD
What am I supposed watching?

Ant P. · Watchman Joined: 18 Apr 2009 Posts: 6920

Ouch, that's bad. Neat that it manages to keep running like that though...

krinn · Watchman Joined: 02 May 2003 Posts: 7470

eccerr0r · Posted: Fri Nov 03, 2017 2:54 am Post subject:

Well unless the clock distribution or all cores share the same l2, a bug that shows up in one core should remain in that core.
However for that second case or any other shared resource, the cores should know an error is coming from the l2/shared resource and would know it's not the core's fault... that is, if the detection logic is smart, it should be disabling l2 chunks instead.

Of course you likely would not get the same error each time but it should happen on the same core - if it were a normal chip problem. Heating the chip is actually a "normal" problem and the error should stay on the same core. All bets are off it was a pre-production chip that had other issues that are not "normal" problems...
_________________
Intel Core i7 2700K/Radeon R7 250/24GB DDR3/256GB SSD
What am I supposed watching?

Myu · Posted: Fri Nov 03, 2017 8:26 am Post subject:

Myu · Posted: Thu Nov 23, 2017 9:31 pm Post subject:

Ok so since then I got one dead motherboard... just brutally stopped working never to be bootable (POST) again

I purchased a second MB (different chipset but compatible) to try to salvage the hardware (it's an i5 and 16GB of RAM after all) but the MCE errors are still present after setting up the new MB and my old Gentoo.

Time for another CPU I guess ?
_________________
Gentoo stable with bits of ~amd64 // Xfce 4.13 + Compiz Reloaded.

NeddySeagoon · Posted: Thu Nov 23, 2017 10:11 pm Post subject:

Myu,

If you have moved all the bits to a mew motherboard, it does not leave much.
That assumes new, not just different.

The CPU cache has single bit error detection and correction, hence it can work correctly with one bit errors.
Two bit errors will always be detected but cannot be corrected, so the core will be shut down.
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Regards,

NeddySeagoon

Computer users fall into two groups:-
those that do backups
those that have never had a hard drive fail.

krinn · Watchman Joined: 02 May 2003 Posts: 7470

Myu · Posted: Fri Nov 24, 2017 6:38 am Post subject:

@NeddySeagoon

Yes indeed, moved all the bits into the new MB but that's not a brand new one since it's hard to find those new at a decent price these days (Intel Core 3rd Gen)

Most of the time the system works fine, correcting errors along the way according to mcelog (as you said, under a certain limit, all goes well), but I'm not keen on keeping it like that if it has a tendency to fry my hardware eventually

I've another test in mind, swap the CPU to another one I have lying around and which is socket-compatible, if I stop getting MCE -> The i5 is probably dead, If not, another piece is faulty.

@krinn

:mrgreen:

I know right, this is getting higher and higher on my troubleshooting list
_________________
Gentoo stable with bits of ~amd64 // Xfce 4.13 + Compiz Reloaded.

NeddySeagoon · Posted: Fri Nov 24, 2017 10:12 am Post subject:

Myu,

Look at the Vcore regulator on the motherboard next to the CPU. It takes in the 12v from the PSU, via the dedicated connector with the black and yellow wires, on converts it to the voltages used by the CPU and RAM. Look for bulging or leaking capacitors.
When they begin to fail the CPU operating voltages are no longer properly regulated.

A motherboard swap and a CPU swap are both good tests.

You would be unlucky to get two failing Vcore regulators
_________________
Regards,

NeddySeagoon

Computer users fall into two groups:-
those that do backups
those that have never had a hard drive fail.

Myu · Posted: Fri Nov 24, 2017 5:43 pm Post subject:

Hello Neddy,

From what I can tell, the VRM's on the MB looks sane, nothing special about them which is good

I swapped the CPU and so far, not a single MCE error in sight, I'll keep this monitored but it seems a clear indication it's the CPU after all.

Thank for your help, very appreciated as always

_________________
Gentoo stable with bits of ~amd64 // Xfce 4.13 + Compiz Reloaded.