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Enrico

macrumors 6502
Original poster
Feb 6, 2007
294
90
Milano / Roma
Hi guys!

I'm debating whether to buy a NAS or use my iMac as a server running 24/7 with an HD connected to it.

I was looking for Power Consumption figures for an iMac that has its screen powered off and Idle, since it would be running this way for the majority of time.

Does anyone have any figures?
I have a 27 Retina with i7, internal SSD and 12GB of RAM.
 

colodane

macrumors 65816
Nov 11, 2012
1,029
470
Colorado
Hi guys!

I'm debating whether to buy a NAS or use my iMac as a server running 24/7 with an HD connected to it.

I was looking for Power Consumption figures for an iMac that has its screen powered off and Idle, since it would be running this way for the majority of time.

Does anyone have any figures?
I have a 27 Retina with i7, internal SSD and 12GB of RAM.

My 2017 (specs below) with the screen off is currently drawing 24 watts. This is measured with an external KilliWatt power meter and confirmed by the iStat Menus total power log.

At this low power the power factor isn't stellar. Mine runs about 0.60 vs. 0.95 with the screen active.
 
Last edited:

Enrico

macrumors 6502
Original poster
Feb 6, 2007
294
90
Milano / Roma
My 2017 (specs below) with the screen off is currently drawing 24 watts. This is measured with an external KilliWatt power meter and confirmed by the iStat Menus total power log.

At this low power the power factor isn't stellar. Mine runs about 0.60 vs. 0.95 with the screen active.

That's great! Sounds like a very low power usage, pretty much similar to a NAS...

What do you mean with not stellar power factor? Maybe the fact that it absorbs 24 watts but in reality it wastes some of that power?
 

colodane

macrumors 65816
Nov 11, 2012
1,029
470
Colorado
What do you mean with not stellar power factor? Maybe the fact that it absorbs 24 watts but in reality it wastes some of that power?

The iMac power supply is a good one and incorporates active power factor correction (PFC). However, these PFC circuits don't typically operate at very low power levels. I was just pointing out that, at least on my iMac, the PFC performance deteriorates somewhere between the normal operating power with the screen on (typically 35 to 50 watts in my case) and the lower 24 watt power level with the screen off.

This should not be a concern. All it means is that with the 0.6 PF with the screen off, the AC line current will be slightly higher than would be expected if the PF were perfect (1.0) The main point is that at higher power levels with the screen on the iMac power supply has truly excellent PF performance.
 
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