Computer Power Consumption

Partizan · Oct 22, 2005, 08:13 AM

I made a little test today. I put a thingy which measures the power consumption into the outlet and started firing up the power users:

Total consumption:
Wifi router, cable modem and ISDN base 40 W
+ HiFi (20 W) 60 W
+ PC (100 W) 160 W
+ Monitor (LCD) (30 W) 190 W
+ Torrent Client & Battlefield 2 (60 W) 250 W (Peak was 270 W)

Why the hell do I need a 550 W PSU????

Regards, Partizan

**dj_stick** · Oct 22, 2005, 08:39 AM

when you buy a 550W psu you buy one that can draw 550w from the wall, not put 550w into your system. A lot of power is lost through heat within a PSU, especially in the transformers and rectifiers - however the better name you buy, usually the more efficient the PSU is - ie a 400w thermaltake and blow away a 450w codegen (i use this example as it's some thing i have witnessed myself)

Matth · Oct 22, 2005, 10:05 AM

Some extra is required to allow for spinup current of hard drives and non-optimum distribution of power drain.

Many cheap PSU models would theoretically only hit their "rated" output, with a pattern of rail loading that is far from common on modern systems.

The major shift over the years has been from the CPU being on the 5v supply, then the 3.3v, then driven by a switchmode regulator from 12v.
WIth the 12v also typically driving the graphics, this means a complete about turn from the days when the 12v rail only powered motors.

In general, forget the supposed "maximum" power, what you need is 12V current rating that is genuine and adequate for the task, with some models now using dual 12v feeds to spread the load.

The quoted rating is supposedly for maximum output power, and even good name models include the little used -V rails in that full load. but ONLY the really good names could be relied on to deliver that maximum with any accuracy and sustainability.

A 550W worthy of the name SHOULD be able to deliver that power to the system if required, for as long as required, and over a practical range of individual rail loadings.

A cheap 550W is unlikely to meet those conditions - the ratings are often inaccurate, optimistic or downright fraudulent!

Partizan · Oct 22, 2005, 12:27 PM

Thanks alot for the explanation guys...

I actually thought my PC is really power demanding, but I see my fears were exaggerated.

Regards, Partizan

Dyre Straits · Oct 22, 2005, 01:33 PM

Just out of curiosity: Did you try playing a heavily demanding 3D Game while doing this test? I'm just curious if there was any significant difference.

The reason I ask is, a video card itself will not pull as much power during normal Windows 2D applications as it will during some heavy 3D games.

Partizan · Oct 22, 2005, 01:56 PM

Quote:

Originally Posted by Dyre Straits

Just out of curiosity: Did you try playing a heavily demanding 3D Game while doing this test? I'm just curious if there was any significant difference.

The reason I ask is, a video card itself will not pull as much power during normal Windows 2D applications as it will during some heavy 3D games.

Please read my first post carefully

regards, Partizan