# Computer PSU power consumption.

Discussion in 'Power Electronics' started by rabbi12345, Mar 27, 2013.

1. ### rabbi12345

3
0
Aug 4, 2011
Hi you guys,

i got PSU with 430W stated in the casing, that would be the DC watt right?
If yes, how much power (watt) is that PSU really consume (in AC)?

Thank you,
Rabbi

2. ### CocaCola

3,635
5
Apr 7, 2012
Depends on how efficient it is, most are in the 75% range so a 430W supply is drawing about 575W...

3. ### (*steve*)¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥdModerator

25,490
2,832
Jan 21, 2010
But practically, the PC will very rarely draw that much power, so the average power consumption will be significantly lower (and the only way to know for sure is to measure it)

4. ### GreenGiant

842
6
Feb 9, 2012
as Steve said it will be a lot less, my friend has a 1200W power supply, running 2 video cards (one requires a 500W one requires a 400W), 4 hard drives and a boat load of case fans. While playing Call of Duty on full specs across 3 monitors it only draws around 400W (based on APC readings) while idling it only draws around 75W

5. ### rabbi12345

3
0
Aug 4, 2011
Hi All,

I will note it down:
1. Efficiency
2. Must test it using Power Meter.

Is there anyway to calculate the DC to AC ?
As PSU state 430W is DC (i think this is max output), can i use the data from the PSU spec for AC consumption?
In the PSU it is state that it needs AC Input :230V , 5 A.
Can i use it to calculate the "roughly" Watt needed?

Thank you,
Rabbi

6. ### GreenGiant

842
6
Feb 9, 2012
based on current standards if it is 80% eficient (thats the most common efficiency) and it being 430W output it will draw somewhere between 0-2.25A at 230V

to get this you multiply the output by 1.2 (20% increase draw to cover efficiency loss) then divide by 230V.
The label that says 230V, 5A is probably just a fail safe because that would be an 1150W draw for 430W supply which is 37.4% efficient (which is terrible), I cant imagine it is that inefficient

7. ### rabbi12345

3
0
Aug 4, 2011
Hi Green Giant,

If i'm not mistaken, if on the PSU is written that output 430W, this is DC right?
As motherboard can't take AC.

And if the input is 230V, 5A, then it will need 1150W, but this is AC right? as the source comes from AC.

So, if i use
input: 2,5A, 230V (AC)
output: 430 W (DC)
can i say it like this, the PSU will drawn around 575 Watt (AC) to produce 430 Watt (DC)?

Thank you,
Rabbi