Re: Power Supply question

oktokie wrote:
I am going to build ATA RAID5 storage using Dell Optiplex GX150(079WPJ
DELL 200 WATT ATX POWER SUPPLY) + Promise FastTrak SX4000 + qty.4 x
WD800 5VDC 0.80A / 12VDC 0.45A.
*May be a CDROM, but CDROM can be removed after building a storage.

Does anyone know how to calculate power requirement for driving qty.4
X WD800 hard drives?
Will 200Watts powersupply give ample juice? or needing to upgrade to
300Watts?

Can someone show how to calculate power requirement?

If you know how to calculate BTU based on power for cooling
requirement, then please, reply.

Thank you.


Generally, with power supply questions, the best place to start is
by looking at the label on the side of the supply. There are a number
of limits on the supply, in terms of the individual rails, combined
rail power limits, and total supply limit.

I found an item here, describing the parts inside the OptiPlex GX150.

http://pcworld.about.com/news/Mar292001id45066.htm

If I go to processorfinder.intel.com , the PIII 933 processor would be
somewhere in the 25-27W range. If you know the SSPEC, you can
look up the exact number for the TDP in watts.

The video card is mentioned as being a TNT2 Pro. That could be in
the 35W range. I don't have a measurement right off hand, but this
power supply estimator page has a bunch of cards you could look at
and compare to. This archived page seems to run fine in Firefox, but
I had some trouble with it in IE.

http://web.archive.org/web/20040411032947/http://www.takaman.jp/psu_calc.html?english

So, there doesn't appear to be a lot of high powered stuff in the
computer, leaving some room for 40W worth of disk drives. One thing to
remember, is during the first 10 seconds, the drives could all
spin up at the same time, and be drawing 2 to 2.5A each during the spinup
interval, for a total of 8 to 10 amps of current from +12V. It could
be that event that "tips the box over", if the supply doesn't have
a generous 12V rail rating. The steady state situation might be better
looking, as then the 12V current drops to your quoted value.

So, give the Takaman calculator a try, have a look at the label on the
side of the supply, and make up your own mind. You have access to more
of the details than we do.

Paul
.

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