[Dx4win] Power consumption of PCs

[Ron Sparks AG5RS]

Pete,

The rating is for both in and out.  BUT... and I repeat a big BUT... Just
like all manufacturers the powe rsupply and ups people "stretch" their specs
using measurement quirks.

First, a 200 watt power supply is a switching type so it draws considerably
more peak current than 200 watts.  Next the UPS is rated at 300 VA not
watts.  So for anything except a pure resistance (which a switching supply
is not) the rating is more like 180-240 watts.

Then, don't forget that the monitor draws about 60-80 watts and if you want
to shutdown the machine during the outage, you will need it.

I have a 300 VA UPS on one computer here and it will just barely carry it
through the sags -- without the monitor.

So, the AG5RS "rule of thumb" is multiply all power consumers by 1.25 and
divide all power suppliers by 1.5.  Doing that would say that for your 2 pc
setup with 1 monitor you would consume 200+200+80 = 480 * 1.25 = about 600
watts peak.  And to get that out of a UPS you would need a 900 VA UPS.  The
absolute minimum, IMHO, would be keeping one PC on the 300 and getting a
400-500 VA for the second PC and the Monitor.

Also, you may want to know that most UPSs I have studied are rated at 10-15
minutes backup at HALF power output.  With a three year old battery you
might get only 1-3 minutes out of a fully loaded one.

Personal experience here: Last outage my five year old 900 VA UPS carried
the PC (300w), the monitor (80w), weather monitor (2w), and the network
router and hubs (15w) for about 2 minutes before it shut down.  Time for a
new battery ($100 - sigh).

Hope this helps,

Ron