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20W when turned off?

Posted: Mon May 24, 2010 10:13 am
by Strid
So I borrowed my friends Wattmeter and tested everything I basically had in the house.

The only shock I got, was that my PC uses 20 watts when turned off. :shock:

I'm glad I know now, so I know that I have to turn off on the socket also, but what could be the cause of this?

I'm using a 200W Pico PSU and Dell DA-2 power brick. Exact specs of my PC is in the signature. The only USB thing I have connected is my mouse, so nothing is charging off the USB ports.

Apart from that, I had 55W idle and 88W full load (doing Fortran vector multipication on both cores and fullscreen glxgears on the GPU).

Anything strange here or any ideas?

BTW: Sorry for posting in the wrong forum. But I swear it was my cat's fault!

Posted: Mon May 24, 2010 1:10 pm
by Wibble
I have recently purchased a wattmeter in order to measure the power draw of my computer (and any other electrical device in the house) and happened across a situation like you have described.

The basis of my computer is an Asus P5Q-EM mainboard, Intel Q9550 CPU and an Enermax Modu82+ PSU.

With the computer on, with Windows booted and no other interaction taking place, the power draw is around 55W. Shutting down the computer - and I do mean shutdown, not suspend or hibernate, the wattmeter displayed a power draw of 30W.

After removing any connected devices apart from the screen, keyboard and mouse and disabling the USB power settings, the power draw when switched off was still 30W. (The screen was connected to a different mains socket to the computer and which was not being measured.)

A little suspicious of the wattmeter, I pulled the power cord of the computer out of the wattmeter, leaving the wattmeter still connected to the mains supply and the power draw was... 30W.

Not until I switched off the mains power to the wattmeter and switched it back on again did the wattmeter display a power draw of 0W, both when disconnected from the computer and when reconnected to it.

I repeated the test using the washing machine and found that the wattmeter tended to display a power draw of 4W when the machine was off - and this machine has a physical on/off switch, not a "soft" power switch.

Measuring the power draw of the computer and washing machine in all other states, the wattmeter correlates with the power consumption displayed by an OWL mains supply monitor so I can assume that the figures I have measured are reasonably accurate apart from when the connected device switches off and something prevents the wattmeter returning to, or close to, zero watts.

Have you tried disconnecting the computer from the wattmeter whilst leaving the wattmeter connected to the mains?

Posted: Mon May 24, 2010 11:06 pm
by Strid
Thanks you for the advice. I will try that! I measured some other stuff, however, which measured 0.1W shut-down. Also the green diode on the Dell DA-2 power brick keeps lighting, when it's turned off. I'll post the results here!

Posted: Tue May 25, 2010 7:52 am
by Vicotnik
My system is 2-3W when turned off (and 3-4W while sleeping). That is with the DA-2 powered (green LED glowing).

Posted: Tue May 25, 2010 9:22 am
by dukla2000
I am surprised at Vicotnik's report - I was going to suggest the DA-2 as I have had a similar problem with 2 Delta bricks. Try plug the DA-2 (only) into the meter (as per my pic Image) and see what watts you get :D