>
> I don't think this has ever come up. With all the
> power splitters available, just how many hard drives
> can you power up with your power supply before it says
> "No mas no mas"?? (courtesy of Roberto Duran)
>
> --
I presume you're asking out of curiosity, but maybe you want to build an
exabyte system to keep all your ripped CDs and DVDs on. =)
Short answer: It depends.
Long answer: It depends on the wattage of your power supply, the total
power consumption of drives, mainboard, processor, RAM, PCI cards, and USB
/ Firewire-powered accessories installed. It also depends on how much heat
your system can take 'cause that's where all those watts eventually go.
Notebook drives typically draw significantly less power than desktop
drives. All drives draw significantly more power when spinning up the
platters, so if you really want to max out your system you'll likely have
to set the 'spin delay' jumper on at least some of your drives. Do ATA
drives have such a jumper, or is this a SCSI exclusive?
Now for a little Math:
W=IV
watts = amps x volts (don't ask me why its I here and A elsewhere =)
To compute the wattage of a hard drive (or anything else), multiply the
current (1mA =.001 A) times the appropriate voltage and sum the 5v and 12v
wattages.
S'pose a drive draws 0.24A at 12v and 0.66A at 5v.
12v x 0.24A = 2.88W
5v x 0.66A = 3.3W
= 6.18W
The beige G3 PS is rated for 150W total output, so (if loaded with nothing
else) it can handle 150 / 6.2 = 24 such hard drives--but this has
overloaded the +12v supply by 0.84A, so you're down to 22 drives. This
ignores the rest of the system, for which it can be difficult to find
exact figures. Check the 'Specifications' section of your manuals but
don't count on finding wattage and / or current draw data. Neither my
10/100 NIC nor my USB card manuals have such data, but they're both
Belkin-branded. Your mileage may vary.
HTH,
Jesse
PS:
Anyone know of sources of such data for, e.g., the G-series processors?
Apple's system boards? Does Apple say how much excess power supply
capacity they provide? Is this correlated to the number of HD bays in a
system?
--
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