Help with amps and dc voltages and house breakers with psu

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Help with amps and dc voltages and house breakers with psu

Postposted on Sun Jun 30, 2013 6:26 am

Ok! Sry if I put this in the wrong category. I have a question about voltages? I use extreme psu calculator pro to configure my system's power supply for my gaming rigs. One thing I have a problem with is burning out psu's, it seems that the breaker draw on the circuit is to much and shorting the life out of my psu's. As can find that the gaming rig i was running died because of the psu failure of the load of the breaker which is 15 amps?

Can someone please tell how to figure out? PLEASE provide simple explanations. This just confusing for me.

I'm looking for buying a new psu here in the weeks ahead and don't want to under draw power and shorting the life of the psu.

What i was using was Ocz modxstream pro 700watt psu half modular. Which died,and which TR recommend i think 4 years ago.
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Re: Help with amps and dc voltages and house breakers with p

Postposted on Sun Jun 30, 2013 6:37 am

Since you are in the USA, you are runing 110/120 V. That means that a 15A breaker will trip when you are pulling >~1,800 Watts. Your computer is very likely not the cause for that. What else do you have on the circuit?
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Re: Help with amps and dc voltages and house breakers with p

Postposted on Sun Jun 30, 2013 7:06 am

Your post is a bit confusing but ill try to explain a few things.

A circuit breaker is a protection device designed to trip when you exceed its rating. If it doesn't trip then you are staying under 15A. Putting bigger breaker wont do anything except create a fire hazard.
A 700W PSU at full load would draw about 6A, give or take. If you are coming close to maxing out your PSU then you should get a higher rated one.
The voltage at the outlet is about 115V nominal, but it will sag under load. How much it will droop depends on quality of the wire, length of the wire and how much current is being drawn. For example, I have a laser printer plugged in to the same circuit as my computer. When printer turns on the UPS switches to battery power because it detects under voltage condition. If you have other equipment on the same circuit as your computer that pull a lot of power then you might be running at slight under voltage. PSU can handle it for short period of time but it could cause additional stress on the components leading to failure.

I suggest getting an UPS for your computer. It will protect you from under/over voltages. Also get something like kill-a watt to see what your voltage and current is at the outlet.
Last edited by infinitybit on Sun Jun 30, 2013 7:07 am, edited 2 times in total.
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Re: Help with amps and dc voltages and house breakers with p

Postposted on Sun Jun 30, 2013 7:06 am

Ok? I have no clue what else is on the circuit breaker. Was using an outlet by the frig, but that was on a different circuit.
And how did you figure out that on a 15 amp breaker is 1,800 watts?
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Re: Help with amps and dc voltages and house breakers with p

Postposted on Sun Jun 30, 2013 7:11 am

P=I*E (for resistive load). 15A * 115V = 1725 Watt.
It gets more complicated when the load is reactive.
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Re: Help with amps and dc voltages and house breakers with p

Postposted on Sun Jun 30, 2013 7:20 am

infinitybit wrote:Your post is a bit confusing but ill try to explain a few things.

A circuit breaker is a protection device designed to trip when you exceed its rating. If it doesn't trip then you are staying under 15A. Putting bigger breaker wont do anything except create a fire hazard.
A 700W PSU at full load would draw about 6A, give or take. If you are coming close to maxing out your PSU then you should get a higher rated one.
The voltage at the outlet is about 115V nominal, but it will sag under load. How much it will droop depends on quality of the wire, length of the wire and how much current is being drawn. For example, I have a laser printer plugged in to the same circuit as my computer. When printer turns on the UPS switches to battery power because it detects under voltage condition. If you have other equipment on the same circuit as your computer that pull a lot of power then you might be running at slight under voltage. PSU can handle it for short period of time but it could cause additional stress on the components leading to failure.

I suggest getting an UPS for your computer. It will protect you from under/over voltages. Also get something like kill-a watt to see what your voltage and current is at the outlet.


I have a Cyberpower System's Green UPS 1,500 VA/900 Watts with AVR- model CP1500AVRLCD

Sry, but I understand the way you put it.
Last edited by Dizzytaz00 on Sun Jun 30, 2013 7:43 am, edited 1 time in total.
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Re: Help with amps and dc voltages and house breakers with p

Postposted on Sun Jun 30, 2013 7:26 am

Well, in this case maybe the PSU just died for no reason. It sucks but it happens.
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Re: Help with amps and dc voltages and house breakers with p

Postposted on Sun Jun 30, 2013 7:46 am

4 years is what I figured from extreme power supply calculator pro. I paid $100 for it.
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Re: Help with amps and dc voltages and house breakers with p

Postposted on Sun Jun 30, 2013 7:53 am

Then if I buy a 1200 watt psu an 15 amp breaker could handle it? For what I understood.
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Re: Help with amps and dc voltages and house breakers with p

Postposted on Sun Jun 30, 2013 8:02 am

Dizzytaz00 wrote:Then if I buy a 1200 watt psu an 15 amp breaker could handle it? For what I understood.

Ah, I get your confusion.

A 1200 watt PSU is not always drawing 1200 watts from the mains supply, it just has that capability should the components in the box require that much power (not likely). Most gaming rigs, even with twin GFX cards, would find a 750 watt PSU overkill for the load requirement.
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Re: Help with amps and dc voltages and house breakers with p

Postposted on Sun Jun 30, 2013 8:10 am

@ Captain Ned
Ok dumb question. (Dizzy moment) How is a 750 watt power supply over kill?
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Re: Help with amps and dc voltages and house breakers with p

Postposted on Sun Jun 30, 2013 8:17 am

Dizzytaz00 wrote:@ Captain Ned
Ok dumb question. (Dizzy moment) How is a 750 watt power supply over kill?

Because the sum total of the components in the box may only require 500 watts of power. Assuming 80% PSU efficiency, the PSU will then draw 625 watts from the wall socket.

A PSU's rating is the maximum power it can deliver to the components in the box. It IS NOT a statement of how much power it will draw from the socket at all times. Socket draw is a function of power draw on the PSU from the components in the box adjusted for the PSU's efficiency at that power draw.

This review is of much older PSUs, but it goes a long way to explaining the concepts (and it features The Beast):

http://techreport.com/review/14064/eigh ... -the-beast
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Re: Help with amps and dc voltages and house breakers with p

Postposted on Sun Jun 30, 2013 10:13 am

Dizzy, link your PC specs for us.

Edit, nevermind - I see your signature now - and you can comfortably run that on a decent 350W power supply. Problem might be what credible just mentioned.
Last edited by Chrispy_ on Sun Jun 30, 2013 7:39 pm, edited 1 time in total.
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Re: Help with amps and dc voltages and house breakers with p

Postposted on Sun Jun 30, 2013 10:22 am

This is probably your issue.

"I have a Cyberpower System's Green UPS 1,500 VA/900 Watts with AVR- model CP1500AVRLCD"


You're, now dead, psu has an "active" pfc, hence you require an active pfc ups, such as this one, known issues with using an avr model with a psu that is active pfc.

http://www.newegg.ca/Product/Product.aspx?Item=N82E16842102131


Hope this helps you.
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Re: Help with amps and dc voltages and house breakers with p

Postposted on Sun Jun 30, 2013 11:52 pm

I thought the problem with active PFC PSUs was that they tend to overload certain *UPSes*, not the other way around?

FWIW, in my experience PSUs seem to be the least reliable component in a PC. Not sure why this is; maybe because they have components in them that tend to run very hot (there's definitely a tradeoff between noise level and cooling of internal PSU components, with many modern PSUs opting for low noise), and must handle much higher voltages than anything else in the PC.
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Re: Help with amps and dc voltages and house breakers with p

Postposted on Mon Jul 01, 2013 12:28 am

Buy properly made PSUs and their failure rate goes to the floor. I've yet to have a Seasonic PSU go bad. I've had similar luck with FSP in recent years. The Antec Earthwatts suposedly have quality builds and so do the Rosewill CAPSTONE PSUs (believe these are actually Seasonic made.)
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Re: Help with amps and dc voltages and house breakers with p

Postposted on Mon Jul 01, 2013 5:30 am

Sry! Off subject, but Everyone it's been a long night. My girlfriend had are baby girl 10 weeks early!

OK back to subject: With active PFC why would it effect a backwards cause effect? I thought it was supposed to help the psu from failure.
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Re: Help with amps and dc voltages and house breakers with p

Postposted on Mon Jul 01, 2013 6:24 am

I have a Power supply that refuses to run when plugged into a UPS, or on a AFCI breaker. Try plugging the dead power supply into the surge protection only part of your UPS ,if it has one. Or just a surge protector strip instead of the UPS. The PFC feature on your power supply reduces the reactive power load and is more important for buisiness than individules. It does not help your computer work any better or longer.
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Re: Help with amps and dc voltages and house breakers with p

Postposted on Mon Jul 01, 2013 2:05 pm

Just for S&G - Active PFC PSUs has issues with lower-ended UPS that don't do actual sine waves but use what's called modified sine waves, the modified sine waves look like trapizoids and this is seen by the ActivePFC as DC, so it cuts power. It's actually a "safety" feature of the ICs that are used.

From a pure technical standpoint, there's nothing about Active PFCs that causes this, but instead it's something built into the ICs. Some Ground Fault and Neutral Fault devices will trigger this as well and it's really sort of the same beast.
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