Let's talk Backup Power Supplies

[metroplex]

I just built a new budget gaming PC (X3 720 / HD 4870) with a Corsair TX750W. I know the 750W PSU isn't being taxed with this system, so I was wondering what size UPS I should purchase.

I really want a UPS to prevent damage during black/brown outs that seem to happen frequently in my area. I don't need 50 hours of up-time, I just need to be able to save my game and shut off the PC.

How is the battery life in these UPS's? Are they just flooded lead-acid batteries?

What brand / model is highly recommended?

 

[Modelworks]

They are mostly sealed lead acid to prevent leaks. Some use gel cells.
UPS are usually sold rated in VA instead of watts. I think because of marketing. 1000VA looks better than 750W
If your power supply is 80% efficient and add another 200watts for monitor I would start looking in the 1400VA range. Since you said you are not maxing out the 750W PSU that should give you about 15 minutes run time on most UPS.

 

[starfireone]

UPS are so you can have time to shut down normally or ride out the quicky 1 to 10 sec outages. You really do not need to spend the bucks for an UPS that will last 15 min.s. If the outage looks like it is going to be more than 5 or 10 minutes than shut your system down. You can get away with a UPS around 950 or 1000 va. I run a 500va ups on a 500ps and 24 monitor with a moden on it too and it last me somewhere around 8 to 10 mins. More than enough time to shut my system down and wait for steady power from the Power company again.

 

[Gillbot]

I used a smaller one but this is the result: http://www.cryo-laboratory.com...cked-my-ups-today.html

 

[metroplex]

Yep, typical car batteries are 50-70 Ah. Heavy duty commercial vehicles can get up to 200 Ah batteries (12V).

 

[PM650]

UPS's rated in watts and VA is a result of power factor. Typically, mfg's assume a pf of 0.6 for the load so watts = 0.6*VA. However, if your psu has active PFC, the UPS VA rating is the full power available from the UPS (for a device with a pf ~=1 - the pc psu). The same is generally not true for other devices (i.e. monitor, chargers, etc.).

 

[Rubycon]

Please consider that if you do indeed install a larger battery on a UPS not designed for extended run time you could endanger yourself or connected equipment! The inverters on small SOHO UPS' have heatsinking just sufficient for perhaps 10 min of use at full load. The exhausting of the internal battery is its safety device. When you add a much larger battery or batteries the inverter can run too long and internal device temperatures increase to levels beyond safe operating limits. These devices will fail - often catastrophically! The battery wiring is fused however there could still be a damaging transient that goes into your connected equipment just before the fuse opens and disconnects the battery.

Larger UPS' employ more heatsink area and/or include a fan to keep them cool under long term use. These UPS' are more expensive and often have connectors for adding batteries. If you must have longer run times these would be your best bet. These are also considerably more expensive as well.

 

[A5]

Back to the topic - what kind of VA am I looking at for running a 550W PSU and a 24" monitor for 5 min? And what brands should I look at?

 

[Modelworks]

Originally posted by: A5
Back to the topic - what kind of VA am I looking at for running a 550W PSU and a 24" monitor for 5 min? And what brands should I look at?

I would look for a 900VA + unit.
That should give you about 7-10 minutes run time. Of course the bigger the more run time and room to grow for future hardware. If you are in an area that has frequent outages then I would start at a 1500VA + unit. The reason is that if your area does a lot of on/off power problems during the day the lower units like the 900VA will not have time to recharge the battery in between the power outages.

So if you are expecting two outages a day then get something larger.

Where I live the power can drop out for just a second several times a day, especially during the summer when everyone runs air conditioning. So I needed something that would handle those multiple times daily well.


APC is as good as any for a brand. There has been a trend lately to make ups with LCD panels, and fancy controls on the front, but I would avoid them. Many people are having problems with those units. You can use software to see what the lcd would be used to display.

 

[A5]

Thanks.