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12v power supply for 24x4.8amp=115.2A12v SCSI drives

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New Member
I am building a RAID array for my home network. i have 24 47GB SCSI drives that im going to run on an HP RAID card. the problem is that these drive require quite a bit of power to spin up. they also require 1.6A/drive for typical usage.

+12V Start-Up (amps): 4.8
+12V Typical (amps): 1.6
+5V Start-Up (amps): 1.0
+5V Typical (amps): .9
Typical (watts seek / read): 24.1
Idle (watts): 22.8
/per drive

i dont care to put 5PC power supplies in the case to run these as i only need the 12v,5v and ground.

I do have the option to add a 20 second delay to 3 drives, and a 40 second delay to 3 more drives, etc in 3 drive sets. if I need to spread the load out over time. But i dont want this to take more than 5 minute to start up and the drives take 10 seconds to spin up.

so i need:
[email protected] AMP &
[email protected] AMP

or a bit less if i delay some drives for a time.

if anyone could help me with either building or modifying some power supplies to do this job for me, it would be greatly appreciated.


New Member
I would just set the delays, or put 5 supplies in the case, it's really not a hard decision. I used to run a 32 processor cluster machine with over 4 terabytes of storage, and I can tell you now that I was never concerned about the time it took too boot up.

First, to keep the power supplies happy in the 2 2-terabyte drive arrays, the drives had spinup delays set on them.

Second, in order to power up all the nodes without tripping the UPSs which were running close to max load I had to start them up in groups of four.

If you want to build big, expect there to be some sacrifices in time to boot up. Personally I don't pitty you that you have to wait 5 minutes for your 1 terabyte worth of hard drive space to come online hehe. :roll:

One other alternative is to buy a large commercial switchmode power supply that supplies +5, +12. However you will find that a $80 PC power supply can deliver as much clean power as some $400 commercial supplies. I have found 100 Amp 5 volt supplies and 40 amp 12 volt supplies in dumpsters before.


New Member

thanks for the help guys. I guess ill just go with the PC power supplies and cope with it.

i was hoping to build something that didn't take up so much space, the 24 drives are large enough already.
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