I think LLC was just placebo, it did not fix the problem. How likely does this sound like a capacitor problem? Thinking of replacing all of the motherboard capacitors.
TL;DR: I have to wait at least a few hours with the computer turned off until I can turn it on and expect relative stability for a day or two, excluding using anything like prime95, that pretty much always freezes it now.
It seems if I turn off the computer for at least a few hours (ex. overnight) and then turn it on, it can stay relatively stable (as long as it doesn't stress the CPU too much, so no prime95, video encoding or anything like that) up to maybe 2 days in a row. When it does eventually freeze I notice that if I reboot immediately, it almost always gets stuck in a boot loop (turns on for 3 secs, turns off, waits 5 seconds, then repeat). If I wait 10 seconds before rebooting then it's like 66% chance it gets stuck in a boot loop instead of making it to POST, and then like 50/50 after 30 seconds, and then like 10% chance if I wait 1 minute. I notice that if I reboot soon after a freeze and manage to get to BIOS settings (UEFI), if I stay on BIOS long enough, maybe 20 seconds or so, the BIOS starts responding quite slowly to my keyboard presses, it feels laggy, and if I try to save & exit, it just turns to a black screen with the cursor and freezes for like 10 seconds and then turns off, and then reboots after 5 seconds and gets stuck in a boot loop. The BIOS does always save though even if it starts lagging and enters a boot loop after exiting, so it can't be a CMOS battery problem. If I wait like 5 minutes after a freeze, the computer gets past POST but it usually freezes at the "Starting Windows" screen. If I wait 10-30 minutes, it usually gets past "Starting Windows" but freezes right after everything loaded (taskbar, windows explorer, network, sound etc.). Anyway I have to wait at least a few hours with the computer turned off until I turn it on again and can expect BIOS or Windows to be running stable and smoothly for a day or two.
Tried these BIOS settings and PC configurations, none of them made any difference:
Disabled Turbo Boost (I now have it always disabled, since it seems to make the computer freeze sooner)
Tried all LLC settings (Auto, Medium, High, Very High, Extreme)
Tried manual CPU voltages (0.900V, 0.950V, 0.980V, 1.000V, 1.050V, 1.080V)
Disabled SpeedStep and all C states
Downclocked with CPU multiplier (16x100 = 1.6GHz, instead of 31x100 = 3.1GHz default)
Downclocked with BCLK (96 is the lowest I could get it to POST, from 100 default)
Downclocked RAM from 1333MHz down to 1000-ish
Increased PCH voltage from 1.050V to 1.090V
Increased DRAM voltage +20mV
Disabled iGPU and using dGPU only
Removed dGPU and using iGPU only
Tried without HDDs, booted Kubuntu live usb (still froze like in Windows) as mentioned earlier
Tried different PSU as mentioned earlier
Literally the only thing that helps keep it stable for at least a day is keeping it turned off long enough, for at least a few hours. Unplugging the power cable and clicking the power button to discharge the system doesn't seem to expedite this process, still have to wait a few hours. I have another CPU (G3258) I could test but I'm not going to bother, it seems almost certainly a motherboard problem, but I don't know whether to gamble on replacing the capacitors. There is no visible problem I can see with these "solid" smd electrolytic capacitors, don't have a multimeter or anything to test with.
Last edited by johnsmythe; 07-04-2020 at 10:13 AM.