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psu power consumption

J

julianbautista87

n00b
Joined
Sep 27, 2010
Messages
5
Hello,

I have this pc:
- Asus m4a785 tdv evo
- Athlon x4 635
- HD5770 vapor-x
- 1 x Hard drive seagate 1500 GB
- 1 x 2 GB ddr3 markvision 1333Mhz
- 3 x 80mm 12V fan
- Thermaltake tr2 600W

I had tested the power consumption of my pc, and I tested my pc with gta4, cod5.

I tested the current in the 120V ac line, whit a small tester.

1001575r.jpg



I got confusing results, When my pc is iddle, the tester shows ~ 0.8 A
When Im playing cod5 whit all max, the tester shows ~ 1.1 A
When Im doing a benchmark whit gta4, the tester shows ~ 1.2 A

power consumption = V * I = 120 V rms * 1.2 A rms = 144 W max.

why? I mean, what am I doing wrong? is it true the psu is only getting 144 W? I dont think so, but I hope you can tell me .

thanks for reading.




-ammeter : multimeter UNI-T UT33A

- I messured the current like this:

22629d1248510942-how-measure-current-current-graph.png


in this draw, the lamp is the pc, and the battery is the 120V line. and the tester was messuring AC current.




my pc should be getting more power, I mean, the graphic card + processor should get 75 + 90 W = 165 W ONLY those parts, so... what am I doing wrong?
 
CPU usually only has around 95W to sometimes 125W I believe now... that's just average.

To reach your full 600W would require a lot more hard drives and a beefier GPU setup

Is there a problem? Or are you just are trying to learn how computers work?
 
Luxor said:
CPU usually only has around 95W to sometimes 125W I believe now... that's just average.

To reach your full 600W would require a lot more hard drives and a beefier GPU setup

Is there a problem? Or are you just are trying to learn how computers work?
Click to expand...


well, my pc should use ~341W according to the specifications of the products I have

- Asus m4a785 tdv evo (~119W)
- Athlon x4 635 (~95W)
- HD5770 vapor-x (~108W)
- 1 x Hard drive seagate 1500 GB ( ~10W )
- 1 x 2 GB ddr3 markvision 1333Mhz ( ~3 W)
- 3 x 80mm 12V fan (~6 W)++

so there must be a problem, I think Im getting something wrong, can you tell me what it is? because I think Im doing right the test....
 
Those are max figures which you aren't going to hit playing a game, or doing anything else for that matter.
 
well, I did the furmark and prime95 tests at the same time, and I got ~250W, maybe you need to do lots more than I did to hit the max figures of my pc components. thanks for the replies. bye bye.
 
119W for the mainboard alone (without taking into consideration the CPU or RAM) is a touch much. Not sure where that figure is from, but it sounds as if that is for the mobo, with CPU and all.
 
Could you get us a better picture of the mulimeter you are using? many multimeters don't offer a range for AC current. Trying to measure AC currents with a multimeter set up for DC currents is almost certain to give meaningless results.

Also the high current ranges on most multimeters are only designed for short duration tests. Neither the test leads nor the meters themselves are rated for long duration high current work.

Also your means of connecting the multimeter looks hazardous to say the least, you have no earth to the PSU, live mains exposed and while I can't tell for sure you may well have undersized cables as well.

Also measuring current of a mains device will only tell you "apparent power" it won't tell you how that breaks down into real power, reactive power, harmonics etc.

In summary an ordinary multimeter is not a suitable device for measuring power consumption of mains equipment.
 
plugwash said:
Could you get us a better picture of the mulimeter you are using? many multimeters don't offer a range for AC current. Trying to measure AC currents with a multimeter set up for DC currents is almost certain to give meaningless results.

Also the high current ranges on most multimeters are only designed for short duration tests. Neither the test leads nor the meters themselves are rated for long duration high current work.

Also your means of connecting the multimeter looks hazardous to say the least, you have no earth to the PSU, live mains exposed and while I can't tell for sure you may well have undersized cables as well.

Also measuring current of a mains device will only tell you "apparent power" it won't tell you how that breaks down into real power, reactive power, harmonics etc.

In summary an ordinary multimeter is not a suitable device for measuring power consumption of mains equipment.
Click to expand...

^ This guy knows what he's talking about.

AC current isn't constant, it's a waveform, the same as voltage. The multimeter may not be capable of properly displaying the RMS current, so you're just getting mumbo-jumbo results because the current is changing faster than the multi-meter can keep track of it.

I'd shell out the $20 for a kill-a-watt and just be done with it.
 
plugwash said:
Could you get us a better picture of the mulimeter you are using? many multimeters don't offer a range for AC current. Trying to measure AC currents with a multimeter set up for DC currents is almost certain to give meaningless results.
Click to expand...

Hi. the multimeter can test ac current

plugwash said:
Also the high current ranges on most multimeters are only designed for short duration tests. Neither the test leads nor the meters themselves are rated for long duration high current work.
Click to expand...

You are completely right on this one, after 15 seconds, currents near 10A could be tested wrong. I think this entirely test could be wrong because of this...


plugwash said:
Also your means of connecting the multimeter looks hazardous to say the least, you have no earth to the PSU, live mains exposed and while I can't tell for sure you may well have undersized cables as well.
Click to expand...

you're right, even when my house has short-circuit proteccion, and I had a fire extinguisher near, the test was hazardous... I was not to do that.

plugwash said:
Also measuring current of a mains device will only tell you "apparent power" it won't tell you how that breaks down into real power, reactive power, harmonics etc.

In summary an ordinary multimeter is not a suitable device for measuring power consumption of mains equipment.
Click to expand...

I know whats an harmonic, but as far as I knew the AC harmonics generally go unnoticed and the distortion is very small. and the reactive power... I though that was more a problem in highly inductive loads, like fatories with lots of motors in their machines


In summary, my test is useless, I must use complex instruments to do what I did.
Thanks for your answer.
 
you are expecting an $18 multimeter to handle the full current of a gaming computer under load, and accurately report the current?
il go ahead and echo everyone else by saying what you are doing is a bad idea. if you sneeze and knock a wire loose, goodbye power supply and probably several components down the chain too, if not the entire computer.
 
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