Amperes required issue

[rodan]

I think I ran into a house electrical power problem in a house I recently help set up a computer. I suspect that the circuit to the room where computer is set up, is not supplying enough
current/amps. I'm not familiar with house wiring, amps, watts, and volts, I just know the basics. What I need to know, first, is approximately how many amps the computer system is drawing, while running.
It's an AMD Duron 1.3ghz, 256mb sdram, has a cdrw, a harddrive, ECS K7s5a mainboard. The psu is a 300 watt, AMD approved, 3.3v - 20a, 5v - 26a, 12v - 13a. This computer runs fine at my house, but, won't run properly in theirs. It sometimes won't boot at all, when shutting down, and cold booting, and, sometimes won't warm boot, no beep code. I've already changed out the psu unit, three times, different brands, 300 watt, to 350 watt. I think the circuit that connect to the receptacles in the room where the room is located, is on 15 amps. Is it possible that the computer is drawing more amps than what is available? The guy who owns the house, says that room is on a separate circuit, so, the only thing running on that circuit is the computer, the monitor, and a printer. Could just those items draw too many amps, and, then, when you try to draw another amp from somewhere, something in the computer fails to run? What is the best way to trouble shoot this?

 

[LiLithTecH]

If the computer drawing more than 15 amps it would trip the circuit\fuse.

Are you powering up things all at once or individually?

Try the PC without the Monitor or Printer on.

I'd be more inclined toward an underpowered AC line.
Only way to check is with a voltmeter and watch for fluctuations.
Nominal voltage in 115vac, Minimal for most PSU's is 90vac.

 

[davettt]

disconnect everything from that circuit ,then if you,re competent check the voltage(with a multimeter or similar)at the outlet,if its low you may have supply problems or problem at fuseboard.if its ok assuming you have a double outlet plug a heavy load such as a kettle or heater into one outlet while testing voltage in the other ,if the voltage drops significantly you may have a problem on that circuit ie;loose connection or problem at back of outlet,the 15a circuit should be fine although i'm only familiar with 220v setups,also make sure youre not doing something silly when setting up the pc (often happens

 

[ZZZZZZ]

Check the outlet with a multimeter and see what the voltage is. (should be between 110V AC and 120V AC. If it isn't then you need to find out the cause of the loss. If it looks normal then leave the multimeter probes in the socket and turn on the computer a carefuly watching for any change in the AC voltage. if the Voltage drops then you could have bad wiring, a ad break or a badd connecting to the bus bar in the electrical panel.

the outlet could also be bad as well. Have you tried the computer in a different outlet on a different circut?

 

[rodan]

Thanks for the tips, will try them out soon. He has a neighbor who has checked the outlets with a 12amp space heater running on it, I think for amps. I'm going to ask him to bring his test equipment, I have a multimeter, too, and we will test for a drop in voltage. I haven't ruled out that the problem may be in the computer, sometimes we overlook the obvious. Just funny that the computer runs perfect, cold boot, warm boot, with no problem, here, at my house, but, not at his. Thanks again for the tips.

 

[gunrunnerjohn]

First off, it's very unlikely that if you get anything from the outlet that you don't have enough power. In the worst of times, a fully loaded computer doesn't draw 200 watts, normally more like 100 watts. The monitor will probably draw 100 or so also. I'd start by checking to see if the ground is good, and the nuteral and hot leads are wired correctly. Next, put it under load, the electric heater is a good idea, and measure what voltage you have, and how much drop there is when you turn the heater on. My guess is you'll find that this is probably a grounding or mis-wired issue, not a lack of power.

I presume you did try it in a different location in his house, right?

 

[Evadman]

Originally posted by: gunrunnerjohn
First off, it's very unlikely that if you get anything from the outlet that you don't have enough power. In the worst of times, a fully loaded computer doesn't draw 200 watts, normally more like 100 watts. The monitor will probably draw 100 or so also.

Ummm...No. My 1600+ on a K7S5A with 2 hard drives, and 2 cd-roms pulls 360 watts from the wall, computer only, and that is just sitting at the login screen. ( tested with one of those watt meter things ) I never did test my monitor though. You are forgetting that most PWS's are 60% or less efficent. so if they make 300 watts for the system, they actually use 420 watts to produce it. the rest is disapated as waste heat.

 

[LiLithTecH]

You are forgetting that most PWS's are 60% or less efficent. so if they make 300 watts for the system, they actually use 420 watts to produce it. the rest is disapated as waste heat

A 300 watt PSU consumes 300 joules of electric each second. (1 watt = 1 joule)

A 300 watt PSU would draw about 3 amps, a pretty safe margin on a 15 amp circuit.

I think you are confusing Watt (standard unit of Power) with Ampere (standard unit of Current)

While it is true that most Power goes unused, the efficiency of a PSU is +/-10%.

 

[rodan]

I presume you did try it in a different location in his house, right?

No, we didn't. I suggested that to the guy, he came back with , " this room is wired on a separate circuit, if it won't run in this room, it won't run in any other room of the house, either". The house is only seven years old, and, his father-in-law wired it for him. Supposedly, he's good at it, supposedly. When we called father-in-law up, he said the wiring is not the problem, without even coming by and testing it. The guy's neighbor came over to the house on Saturday, and tested the circuit through an outlet while having a 12 amp space heater running. I wasn't there, so, don't know if their was a voltage drop. The guy says the neigbhor mentioned that if their was enough amps to run the space heater, the computer should run fine. Next time I'm at their house, I'm going to ask for the neighbor to come over with his test equipment, and, we will test the outlets with space heater and computer running, see if their is a voltage drop. Something I did find out, the lady of the house said that the local electric company said that area she lives in is prone to low power provided, at times. She said she does get lots of power outages there, too. Oh, and, one more thing, but, I don't think this would be an issue, but, I thought it a bit odd,,,, his father-in-law put eight outlets in the room, and, it's a very small room.

 

[Mark R]

Ummm...No. My 1600+ on a K7S5A with 2 hard drives, and 2 cd-roms pulls 360 watts from the wall, computer only, and that is just sitting at the login screen. ( tested with one of those watt meter things )

Are you sure? I've tested a number of PCs, using a good quality energy meter. The most powerful I tested was a fully loaded Athlon 1.1 GHz (overclocked), with 2 HDs, 2 CD-Roms, and filled with cards (including a Voodoo2 in addition to the main accelerator). This would take 150 W (running Q3) - approx 110 W when idle. You must have a massive heat pump or several processors/graphics accelerators for that to be accurate.

One possible confusion, is that some cheap watt meter devices don't measure Watts (power) but Volt-Amps (Volts x Amps) which are not the same thing. A standard PC power supply has a power factor of 0.6, which means that Volt-Amps = Watts/0.6 - The above PC was probably drawing 250 VA at full load.

VA is what your wiring has to cope with, W are what you pay for.