good 8W idle power spikes to 14W & doesnt go back down again until reboot

good day all.

I am new to unraid, & this is a power usage related issue, so please go easy on me. 

I'm having a problem whereby my optimised idle power usage is good initially, but those optimisations fail after a period.  I’ve read a myriad threads that deal with low power optimisation, but I’m yet to find one where this happens (still looking though).

just to explain the background/setup, this is an all flash, quiet, low power NAS.  my data is mostly static, accessed only a few times a day & I don’t need high speed access (1Gb lan is perfectly fine). 

The hardware is a HP elitedesk 800 G3 SFF (i7 7700).  it has 4 PCIe slots (each loaded with an NVME via adapter card) plus an additional nvme in the native M.2 slot, giving a total of 5 NVME drives.  this is mostly an experiment to decide if investing £500-£700 in a F8 SSD or Lincstation n1 is worth the money (probably not, if i can fix this idle power issue).

A clean unraid (xfs with or without parity), 4 apps installed (autotweak, tips'n'tricks, fix common problems & powertop) and every power mode set to save, super save, boost off etc yields a perfectly reasonable 8-watt idle usage (measured at the wall, with multiple meters to verify accuracy).

This 8W idle will continue for a while (maybe an hour, maybe 5), with small spikes every now and then as the server is access etc.  but at some point, one of those spikes locks the idle power usage at ~14W & it doesn’t drop again until the unit is rebooted (this effectively doubles the power usage for no obvious reason)

all power mode timers/schedules are disabled, the native power mode is set to best efficiency & every other bios/unraid setting i can find to reduce power is set accordingly.  There are no VMs or docker containers setup.

At idle all the NVME drives are reporting ~0.01W usage in unraid & low to mid 30's temps, so nothing is getting hot &/or throttling.

powertop does confirm the C states shift negatively when this issue occurs, with most of the CPU being 80%+ C8 beforehand and a roughly 60% C8 20% C6 split after the idle spike. all 3 C state measurement headings show lower C states afterward.  a reboot returns the 8W & higher C-States.

I can see no glaringly obvious entry in the GUI logs that indicate something significant changed between the 8w & 14W idles. 

On several occasions i thought it was the web GUI that triggered it, however even after logging out and leaving it for hours, the lower 8W idle doesn’t return until rebooted.

just looking for some idea what to try next really, as I’ve just about maxed out my current experience with unraid.  ive also tried many more things that i can't list here, for the sake of not making this post a mile long, so ask away.

Thanks in advance 

P

Edited January 17, 20251 yr by satmanuk