Forum Thread

UPS for computer

ndj123 530 22 December 25, 2015 at 07:27 PM
Hello,
I need a UPS for a computer with power consumption about 350W max. Not going to connect neither monitor nor other external devices. If it supports automatic switch to hybernate under linux, than just need enough capacity to save say 24GB of RAM to a hard drive. Probably 10min capacity is enough.
I haven't seen blinking bulbs etc. on the electrical network of interest so I believe the electrical network is quite safe. Though I need to do long computations on CPU (GPU is not used).
Don't have a particular computer yet, most likely it will be Dell T20 or Thinkpad TS140 with xeon CPU.

Can smbd clarify why there are usually 2 different numbers in specification of UPS: VA and Watts?
Shouldn't they be the same?

3 Comments

1

Sign up for a Slickdeals account to remove this ad.

Joined Nov 2013
L5: Journeyman
530 Posts
22 Reputation
Original Poster
#2
still looking
Reply Helpful Comment? 0 0
Joined Nov 2013
L5: Journeyman
530 Posts
22 Reputation
Original Poster
#3
still looking
Reply Helpful Comment? 0 0
#4
I have setups just like what you're describing making up my homelab. Both a t20 and two ts140s. I have an APC Backups-NS 1080 that can power two of them, at average load, for about 45 minutes. This includes 4 hdds, 2 ssds, and a 27 inch monitor. Spent about 100 on the UPS. Really total overkill, but it's nice to actually try to just wait-out the 5-15 minute outages, then have a shutdown start. As far as platform support goes, what you really want is USB-hid support from the UPS. This gives modern OSes the ability to read the battery state, just like a laptop, without additional drivers. I have an SPI-600 that runs my network gear. Uses an old serial over USB protocol, and I've had to jump through a number of hoops to get it up and running. If you want multiple hosts on a single non-network UPS, you want network ups tools, or NUT. FOSS, I'm in the middle of configuring a linux VM with it for deployment in multiple scenarios.

VA and Watts are effectively the same for "dumb" loads, say an incandescent lightbulb. This is an average over a full period of the power cycle.

The switch-mode power supply in many modern products, including computers, pulls power only during parts of the cycle. The average power consumption is similar, but can result in noticeably higher peak loads. The Watts rating on a UPS is thus a de-rating of VA to an approximation of what size PC power supply can be handled.

It is also important to note that a lightly loaded high-wattage PSU can, in certain instances, overload your UPS. A power supply that has been totally drained may, when supplied power, temporarily pull it's full wattage while the filter circuits recharge. We're talking fractions of a second, but I have seen it cause a battery backup to fail.
Reply Helpful Comment? 0 0
Page 1 of 1
1
Join the Conversation
Add a Comment
 
Copyright 1999 - 2016. Slickdeals, LLC. All Rights Reserved. Copyright / Infringement Policy  •  Privacy Policy  •  Terms of Service  •  Acceptable Use Policy (Rules)  •  Interest-Based Ads
Link Copied to Clipboard