Sleep Saves Power

Update: See below.

I’m sure you all know this, but I had to try it for myself.

Three Computers Running

294 watts for 3 computers idling. Not running any particular load. And now Sleeping

Three Computers Sleeping

Only 39 watts if they are all sleeping. You probably all know this, but I have avoided sleep for years since way back when I tried it and often couldn’t wake up the computers and had to reboot them. Back in the Windows 95 Days or some such.

Well now with Windows 10 I’m giving sleep a try again. We’ll see. But based on this kind of power saving I’m willing to try it again. I plan to set them all to sleep if no activity for an hour.

This is the configuration measured:

  • Core i7 950, SSD, One 650 HD.
  • Core i5 4570, SSD, 1TB HD, 2TB HD
  • Core i7 4770, SSD, 2TB HD, 4TB HD
  • UPS, 4 Port DVI KVM switch, 24″ Monitor on standby

10 watts for a sleeping computer isn’t bad.

Update: Windows 10 sleeps all night, but does not go to sleep automatically.

I could not get these systems to go to sleep automatically. Despite lots of research and disabling LAN wake up of any kind, and looking for applications that might be keeping them running. I could not figure out why the systems would not sleep automatically. But when they were put to sleep manually with the power menu, they stayed asleep all night or longer.

If you want to do this, I suggest you enable Hybrid Sleep. My systems are on UPS [Uninterruptible Power Supplies], but if the power goes out its best if they can wake up from Hibernate as well as sleep. Hibernate writes the system state to the system disk [SSD in this case] so it is safe from a power outage. Sleep keeps a little power going to keep the memory alive and if the power dies, the system will lose any work that was active.

Most of my systems had Hybrid Sleep available, but one did not. After going through the settings in the 6 different ways to get to the power settings, there was no Hybrid Sleep or Hibernate options. Again, despite lots of research the only way to enable Hibernate, and therefore Hybrid Sleep, was to use the powercfg program directly. If you can’t find the Hybrid Sleep setting use Run As Administrator to run a command line window, then use the command

powercfg -h on

to enable hibernate.

While I’ll have my screens shut off after 15 or 20 minutes as I always have done. I guess I’ll have to manually sleep my machines. It is just too complicated to figure out what is keeping my systems from going to sleep by themselves.