Need to know power consumption.

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Processor:        Intel Core 2 Duo E8500 3.16GHz
Motherboard:    Asus P5E3 Deluxe with Intel X38 chipset
Ram:                Mushkin Enhanced 2x1GB DDR3 1333MHz;
Graphics Card: Asus GeForce 9800GTX 512Mb
Sound Card:     Creative SoundBlaster Audigy 2 ZS
Harddisk:          2 x WD120GB and 1 x WD320GB
DVDRW:          Pioneer 18X drive

This is the spec for my system. Need to get a PSU. Can anyone calculate how
much power I need ? Also I'm running RAID 0 on my two 120GB drives.


Re: Need to know power consumption.

Jerry Chong wrote:
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65W for processor. Assuming Vcore converter on motherboard is 90%
efficient, this is 65W/12V * (1/0.90) = 6.01 amps from 12V2

The motherboard and the RAM, together, might take 50W or so.
This is just an estimate, based on some measurements of older
motherboards here (I use a clamp-on DC ammeter, connected to the
wiring harness of the ATX PSU). The 50W could come from 3.3V
or 5V or a mixture. Each motherboard design is different.
(You can increase this to 60W, for those motherboards where
the chipset runs obviously hot. The RAM component is pretty
small now, and only a couple watts per stick.

9800 GTX power is listed here.

46.6W/12V = 3.88 amps through the slot connector
(31.76W+28.584W)/12V = 5.03 amps through the two PCI-E aux power connectors

On a dual rail supply, all that current flows from the 12V1 output rail.

Hard drives are estimated at 12V @ 0.6A for motor and 5V @ 1A for logic.
When a hard drive spins up, the 12V rail is loaded up to 2.5A per drive,
as the motor accelerates the platters for the first 10 seconds. Generally
speaking, a separate, power-up power calculation taking motor current
into account, is only needed for more than 4 hard drives.

Optical drives may have numbers on the label. I use 12V @ 1.5A for motor
and 5V @ 1.5A for logic, for example. Depending on features (like Blueray),
some of the fancier optical technologies might be up around the 2.5A level.
The motor current should only be drawn while media is present in the drive.
You cannot really say much about the logic current - I assume it is always

For cooling fans, I assume 12V @ 0.5A from 12V1, as a placeholder. Numbers
are printed on the label of many fans, for more exact estimates.

Total so far -

12V2 = 6.01 amps (processor only, is on 12V2)
12V1 = (3.88 + 5.03) + 3*0.6 + 1*1.5 + 0.5 = 12.71 amps

3.3/5V power = 50W + 3*5W + 1*7.5W = 72.5W (compare to combined rail rating)

For total system power, I throw in 5VSB * 2amps for standby.

Total system power = (6.01+12.71A)*12V + 72.5W + 5*2 = 307.1 watts

Total system power would be seen while gaming, with a game CD in the drive.
Other scenarios may draw less power.

The dominant number above, is the 12.71 amps on 12V1. You should meet that
number first. Throw in 3 amps margin, so perhaps a 12V1 @ 16A is a good
target to aim for. Maybe you'll end up at about a 500W level for the
PSU. For example, this 500W Seasonic looks about right, and meets my
targets for minimum 3.3/5V currents (>20A), meets the 12V1 needed,
meets combined powers, and so on. If you plan on overclocking, then some
of the numbers would need to be scaled appropriately. (Lots of
room on 12V2 to overclock the processor.)


Re: Need to know power consumption.

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Check out:

On-Line calculator for Power Supply.

Re: Need to know power consumption.

On Tue, 13 May 2008 22:58:48 +0800, "Jerry Chong"

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Decent brand, current generation, 500+W.
Sometimes you can find good deals and get a little higher
wattage for not much if any extra money, the key being to
keep an eye out for deals rather than being forced to buy on
a moment's notice.  

Re: Need to know power consumption.

Jerry Chong wrote:
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75 watts.

Claude Hopper          :)

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