I have a Dell XPS 7590, with an Intel® Core™ i9-9980HK CPU @ 2.40GHZ processor. The expected number of cores for this device are 8 with 16 threads. However, neither in the BIOS nor the OS (I'm running PopOS) does it show 8/16. Instead it shows 7/14. Suggesting that a core is dead. I've never encountered this problem before. Can just a single core die?
Yes, a single core on a CPU can die. It is unusual for it to manifest this way, usually it would cause instability rather than be outright missing. Pop the CPU out and look for bent pins in the socket or thermal paste gumming up some of the pads on the bottom of the CPU.
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7Individual CPU cores don't have many dedicated pins (do they have any at all?), so I seriously doubt this will help. – Dmitry Grigoryev Oct 27 '20 at 12:40
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7Also the user is using a laptop with a soldered cpu so I don't think this is an option. – akaltar Oct 27 '20 at 13:00
I reset BIOS to factory settings and on my next reboot, all cores expected showed up.
I believe I may have updated my BIOS while having a number of cores turned off (for battery life) and perhaps it was unable to account for it in the process somehow.
cat /proc/cpuinfo
andsudo dmidecode | awk '/Intel/,/^$/'
. Lastlydmesg
may also have some info on CPU detection during startup that may be relevant. – Mokubai♦ Oct 27 '20 at 7:08