Random hard reboots during heavy compilation on Slackware 15.0 - PSU aging or kernel panic?

[jalah93190]

Hi everyone,
I’ve been running Slackware 15.0 on my main daily driver for quite a while now, and generally, it has been the rock-solid experience I’ve come to expect from this distro. However, over the last two weeks, I’ve started running into a really frustrating issue that has me scratching my head, and I’m trying to determine if this is a software configuration issue or if my hardware is finally giving up the ghost.
The behavior is abrupt: the system performs a hard reboot without warning. No kernel panic on the screen, no freezing mouse cursor beforehand—just a sudden click and a restart.
I first noticed it while compiling a custom kernel. I usually run make -j12 because I’m on a Ryzen 5 3600, and about 10 minutes into the process, the system just cut out. My first instinct was overheating. I installed lm_sensors and monitored the temps while putting the system under load again. The CPU never went above 70°C, and the GPU (an older RX 580) was idling. So, thermals seem fine.
I dug through /var/log/syslog and /var/log/messages hoping to find a segfault or some error right before the crash, but there’s nothing. The logs just stop and restart. This lack of software logging is leading me to believe it’s a power delivery failure.

Here is where I could use some advice from the hardware gurus here. My rig isn't exactly power-hungry, but I have recently added three mechanical hard drives to set up a local RAID array for backups. The machine is currently powered by a generic 500-watt power supply https://serverorbit.com/power-supplies/ ... r/500-watt that I salvaged from an old office workstation years ago. It’s definitely not a "Gold" rated unit; it's just a standard workhorse I had lying around.
I know that capacitor aging is a real thing, and reliable power distribution is critical, especially when all cores are at 100% and mechanical drives are spinning. I suspect that the sudden spike in power draw during compilation, combined with the spin-up of the drives, might be tripping the over-current protection on this old 500-watt unit. It feels like the 12V rail just sags too much and the motherboard cuts power to protect itself.
Before I go out and tear my cable management apart to swap the unit, I wanted to ask:
Has anyone experienced similar "silent" reboots on Slackware that turned out to be software/driver related (maybe ACPI or C-states)?
For a Ryzen 3600 + RX 580 + 4 HDDs, do you think a modern, high-quality 500-watt unit is still sufficient headroom, or should I be looking at 650W+ to be safe?
I’d prefer to stick with a 500-watt unit if possible just to keep the efficiency curve tight for idle usage (since this machine runs 24/7), but stability is obviously the priority.
Thanks in advance for any insights!