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Ideal PSU for 24 HDD home server?


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I'm currently building a medium-scale home server with the capacity for 24 HDDs (3tb in size, standard platter 5200rpm with an average power consumption of 5 watts under load) for the RAID array and 1 single 1tb drive for my OS.... but I have no idea what type of a power supply to choose!

I have some experience with Corsair PSUs (and I love them since I've never experienced a failure in all my years building systems) and I'm hoping I can come up with an option or two here!


The server casing I'm using has six backplanes with one single 4-pin (molex) power slot per backplane.

Each backplane will host four of my 3tb drives.


My worry is that if I were to run 8 drives off of a single rail that I'll stress and burn things out faster than typical for a PSU. That said, I'm not sure just how many PSUs Corsair has on the market that have six sata/peripheral device rails to support a configuration such as this (my OS drive would be chained to one of these as well but averages 4W under load as well so 5 rails would be approximately 20watt usage with the 6th sitting at approximately 24watts usage.


I believe that a 750 (or even 850) watt PSU should suffice since the cpu/board are fairly low consumption and the RAID controller I'll be using eats about 150w.


I was hoping to come to conclusions on my own but I've also concluded I could use some help understanding a few things (as I may have a few misconceptions about power draw requirements)! :)

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you will need a ton of SATA cables, spliiters for Molex are low cost too


seagate has some 10TB disks now, that would cut down on the number of drives big time


I'm sorry I didn't clarify.. I'm using an SAS RAID card and the backplanes have a single SFF-8087 port that automatically routes to the drives (this means it's one single cable per four hard drives from my raid controller). ;)


Again, my concern is just how many drives can I SAFELY run on a single power-cable from the PSU? I'm used to having only 3 sata/molex connectors per cable (meaning 3 devices tops normally).

The way this case is designed is that one molex connector will power 4 drives simultaneously.

Is it safe to power 8 per rail/cable?

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Each string of three SATA molex connectors is not necessarily considered a "rail", in power supply parlance, in and of itself. I personally have always specified "single rail" power supplies for my builds because I feel that having one rail loaded and another rail unloaded in a multi-rail power supply is inefficient and could lead to over loading the power supply if you aren't careful in the way you balance the loads across the rails.


I know a discussion of pros and cons of single vs. multi rail power supplies is not what you asked about but your mention of power supply rails made me think about it.


That being said, the guage of the wire used in molex cables is more than enough to support eight 5-watt drives (40 watts) per cable regardless of the power supply's internal configuration.


Good luck with your build!

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