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Are AVR's important to have to back up a PSU?

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October 25, 2009 9:46:38 AM

I use an APC 500watt back-up, the thing is, my PSU is a 550W realpower 80plus psu..... does this make sense? I know I dont go over the 500 or actually 600watt threshold/max with my current system, but does it still makes sense to have an AVR less than my PSU??

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October 25, 2009 4:05:02 PM

Typically an APC 500 is rated for 300 watts... might want to read up on the particular model you have to verify this.

At work we put in a new phone system that required very power hungry PoE switches... and these new switches pulled way more power than our APCs could handle... so every time the power blinked, the APC would go into a panic mode of sorts and just continuously beep. At that point our closet lost power and we had to manually reset the APC.

It won't hurt to try to see if that APC can support your system. Just bring up your system on the APC and then unplug the APC from the wall. I suspect it will work fine because there's no way your system is pulling 550 watts... especially at idle.
a b ) Power supply
October 25, 2009 10:40:47 PM

It's wise to size the PSU for your computer at about double the capacity that's actually required - this is because PSUs are usually most efficient at about 50% load and therefore you'll be pulling the least amount of power from the wall socket.

If this is the case with your system, then what's really important isn't the PSU rating but rather how much power the supply is actually drawing from the wall. This is can be measured with a device such as a Kill-A-Watt (easy to find using Google).

Note that a 500W power supply which is actually running at it's 500W capacity will actually be drawing MORE power from the wall because no power supply is 100% efficient. For example if the power supply is 80% efficient it will be drawing more than 600W from the wall.
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October 26, 2009 12:28:00 AM

liquidsnake718 said:
I use an APC 500watt back-up, the thing is, my PSU is a 550W realpower 80plus psu..... does this make sense? I know I dont go over the 500 or actually 600watt threshold/max with my current system, but does it still makes sense to have an AVR less than my PSU??


So many people get this wrong...

there is a relatively cheap meter that those in the US can get, called the Kill-a-watt (I think). I'd bet that your system doesn't pull more than 2 amps from the wall, (240 watts total) with everything plugged into the UPS. By 'everything' I mean monitor, routers, cable modems, phone chargers etc., and running prime 95 and some 3dmark test all at the same time.
October 27, 2009 4:56:16 PM

At work we had APC 350s that were loaded with nearly double their rated load (per Cisco & APC) and they worked sometimes... once we put in larger batteries that were at the rated load, things were a lot smoother. In my case the equipment running on our APCs (24 and 48 port PoE switches) were in fact pulling close to their maximum power (all ports were in use and all ports had PoE active)

Obviously using a Kill-A-Watt

http://www.newegg.com/Product/Product.aspx?Item=N82E168...

Would clear up a lot of the uncertainty on this topic. The only point I was trying to make is that an APC 350 is NOT rated to support 350 watts of power draw... nor is an APC 500 rated to support 500 watts of power draw.
October 28, 2009 6:23:16 AM

sminlal said:
It's wise to size the PSU for your computer at about double the capacity that's actually required - this is because PSUs are usually most efficient at about 50% load and therefore you'll be pulling the least amount of power from the wall socket.

If this is the case with your system, then what's really important isn't the PSU rating but rather how much power the supply is actually drawing from the wall. This is can be measured with a device such as a Kill-A-Watt (easy to find using Google).

Note that a 500W power supply which is actually running at it's 500W capacity will actually be drawing MORE power from the wall because no power supply is 100% efficient. For example if the power supply is 80% efficient it will be drawing more than 600W from the wall.



THe APC is an AVR (Automatic Voltage Regulator), its not the PSU but it compliments the PSU with cleaner power as it has a transformer and stabilizes power as compared to directly from the outlet......

My AVR is 500W and my PSU is 550 80plus.... but it works fine as my system doesnt go past the 550-600power threshold anyway.....
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