Processors

[GhostrydeID]

I've got a 23 month old 5900x that I don't even use PBO on and just run stock CPU settings, as the system is faster stock than with PBO enabled. I discovered OCCT today and went to run some stress testing to check the cores before trying my hand at under volting, and discovered my CPU was only showing 11 cores. I then ran CPU-z to double check, and it also shows only 11 cores, so I checked in the BIOS and sure enough, only 11 cores. I have no idea what happened to the other core, or to be honest, if it was ever there. It never occurred to me that a core wouldn't even register or that the CPU would function "normally" with a dead core, so I haven't checked my core count previously.

Is there anyway to reset the CPU and kick the missing core into gear (I tried resetting it in Ryzen Master), or am I just screwed with a bunk 23 month old CPU with an MIA core?

[schldskjoirz]

Things you could try... reseat the cpu and before that check the pins. Perform a cmos reset. Uninstall the chipset driver and reinstall it. Uninstall Ryzen Master and remove all its remnants. You could also run msconfig just in case and check out the boot/advanced options that the settings are there at the default state. If none of these work then indeed the cpu may have one malfunctioning core.

[goodplay]

So your seeing core count as '0-10', not '0-11'? 

[GhostrydeID]

It is a 12 core CPU and it is only showing 0-10 cores in software and BIOS. I'm dubious about windows drivers or Ryzen software having anything to do with it, since the BIOS is also reading only 11 cores. I tried updating my BIOS to 37a (Gigabyte Aorus Ultra X570), but the BIOS update didn't resolve it. The pins are intact, thermal paste was/is spread evenly, there is no visible damage on the CPU and as we speak the CPU is running at 48c. I went ahead and tried undervolting and everybody else reports being to run a negative curve of -25 to -30 on the 5900x and -13 was the best mine would do. And that's not even just reporting errors, anything lower than -13 and the system would straight up crash and reboot. I definitely lost the silicon lotto. *sigh*

[GhostrydeID · Accepted solution]

I got it resolved. It took clearing the CMOS and going back to the original BIOS, then flashing back to F36 BIOS afterward, but they are all registering now. Friggin weird! Never seen a core drop off before. I spent the day working on that and then test runs on the under volting, but I succeeded. Cores 2, 3 & 5 I could only do a negative curve of 12 on, so my best guess is it was probably one of them that dropped completely off. (Since I was missing a core entirely, I don't know that I can trust my core numeration to be the same as it was before, so I'm not sure which core was the problem).

[schldskjoirz]

Wagnards CPU Core Analyzer is a handy tool to find problematic cores and threads. If you haven't used such apps, try it with some benchmark tool. It shows right away if any core is malfunctioning. If a certain core gives abnormal readings constantly, it's time to RMA the processor.