Sunday, June 14, 2015

pfSense on Core2Duo E8400 refurbished PC

A rough power estimate for my little SFF (small form factor) refurbished PC that I'm using for a pfSense firewall:

  • Intel Core2 Duo E8400 @ 3GHz
  • 4GB RAM
  • 120GB SSD
  • Dual-port Intel PCIe x4 NIC
At idle, it consumes about 38W when the CPU throttles back to 1.8GHz.  That's pretty good for a PC that is not designed to be a low-power / fanless unit.  Under load, that goes up to about 60-65W.

38W @ $0.15/kWh = $50/yr
65W @ $0.15/kWh = $85/yr

So even if I got something that stayed below 15W, I'd only save $50-$60/yr.  A lot of the low power units are $300-$500, which would be a very long time before they'd pay off.

Note: You do need to enable PowerD under System -> Advanced -> Miscellaneous -> Power Savings in order to get the CPU to throttle down when idle.  I recommend "Hiadaptive" for an office firewall, but you might want to experiment.

The biggest CPU hog on my current pfSense setup is "ntopng".  While doing bi-directional gigabit testing, that ate up 10-12% of my CPU power.

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