Estimating System wattage

[Christopher Snook]

Rich Emberson wrote:
> So, I recently built a new system. I figured out what
> motherboard I wanted, what cpu, how much memory and
> disk and then I when and used a couple of the online
> system wattage calculators and got somewhere between
> 500 to 650 watts. I could not get (find) a PSU
> with the right connectors for the motherboard so
> I ended up getting Silverstone Zeus 750 watt supply
> (yea, overkill). I then got a UPS from a local store.
> They had a sale and a higher end UPS turned out to
> be cheaper than a 600 watt unit, so I got a
> APC UPS BX1500LCD (865 watt) (again, overkill but nice).
> What is interesting about this UPS is that it can
> show the current wattage used by your system on its
> LED (along with other stuff).
> Now, my strategy for constructing the new system was to pick
> a motherboard that was build for high-end power and then
> pick cool components; I am a developer, not a game player
> and this system will house MythTV and Asterisk someday,
> well as serve as a development box.
> So, what I ended up with was:
> 
>     ASUS P5Q Deluxe
>     Intel quad core QX9550
>         95 watts max for $550
>         (the QX9650 is 130 watts at $1000)
>     8GB CORSAIR (DOMINATOR) TWIN2X4096-8500C5DF
>     Asus EN7300GT silent graphics board
>         idle: 8.7 Watts
>         max: 16.1 Watts
>     2 WD VelociRaptor Model: WD3000GLFS 300
>         Read/Write  6.08 Watts
>         Idle        4.53 Watts
>         Standby     0.42 Watts
>         Sleep       0.42 Watts
>     2 WD Caviar GP Model: WD10EACS 1 TB
>         Read/Write  7.50 Watts
>         Idle        4.0 Watts
>         Standby     0.97 Watts
>         Sleep       0.97 Watts
>     ASUS V60 cpu cooler (overkill)
>     SAMSUNG  SH-S203N DVD/CD RW
>     Logitech SBF-90 Black 3 Buttons 1 x Wheel
>     Logitech 967738-0403 Black 104 Normal Keys
>     SST-ST75ZF Zeus power supply (overkill)
>     APC UPS BX1500LCD (overkill, but very nice)
>     Lian Li PC-A71 Black (overkill, but very, very nice)
>     BIOS 0803
>     Fedora 9 64
> 
> Now, with no applications running, idle, according to the UPS
> the system uses 70 watts.
> The highest wattage I can get it to use running bunches of
> parallel compiles is about 125 watts.
> 
> My question is: whats with the online wattage estimators?
> Are they all implemented by folks selling power supplies
> who want to sell users bigger ones than are needed?
> 
> In terms of power needs, I ended up way over-specing $$ the system.
> Basically, I ended up with a system that
> uses as much power as a 120 watt light bulb.
> 
> Richard
> 

You only need massive power supplies in a desktop if you're running high-end 
video cards or something else that needs separate power inputs.  Enjoy your very 
long UPS runtime.

-- Chris