How neededd this system is?
If not essential, you should try to:
- Remove BIOS battery, put the CMOS clear jumper on for 10 minutes
- If you have time, leave the MoBo overnight powered OFF, without battery after CMOS cleared.
- Turn on the system and export all Zpools for the next step
- Remove Every component from the system (all, but one RAM stick, HDDs, SSDs, NIC), except for the absolute minimum (CPU, MoBo, 1 stick of RAM, TN boot pool) to boot the system .
- Disconnect ALL USB devices and hubs from the system, besides the keyboard and mouse ( however, nor keyboard, nor mouse is not even needed to run this system)
- If you have a spare monitor, attach it to the system to be able to see the console output. It can give you hints about any possible HW failures.
- Run this barebone system for at least 1-2 days
- Boot another OS (live linux is OK for that, you dont have to install it, just write out on a 4+GB USB drive), if you have access to it and check stability with that too
- If you have still time, run an endless loop of Memtets on this barebone system for a couple of days.
- How old is your power supply? check the internals of it for dust.
- Check the thermal paste on the CPU, wipe it off and apply a new layer of it.
- Check ALL fans in the system, for slow rotationg ones.
- Check all sATA cables. The cheap ones are prone to just simply cause wacky connections and slow down the full system (however, this is not really likely, since you did not have data errors on your pools.)
- Run an extended SMART test on your boot drive.
- If you are not using the original NIC on the motherboard, disable it in BIOS.