power supply wiring question


anonomouse

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Hi looking for advice with wiring new icy dock 5-3 cages

i want to use the stock cable from psu that has 3 molex connectors, paired up with x3 4Pin Molex Male to 3x 4Pin Molex Female Extension Cable like these http://www.superbiiz.com/detail.php?name=CA-M3MK all connected to cages

will i have any power issues having 9 drives currently then 15 eventually all hooked into one socket on psu ?

 

my psu - SeaSonic X Series X650 http://www.newegg.com/Product/Product.aspx?Item=N82E16817151088

 

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If I understand you correctly, you want to connect up to 15 drives to 1 single cable that has 3x 4-pin on it using adapters?  If that is what you are saying, then not really a good idea.  You should try to balance the load better across the 8x 4-pin connectors that modular power supply offers.  To tell you if the power supply can support 15 drives assuming the load was balanced, would need to know the specs of the system.

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there are 5 peripheral sockets on the PSU that i can use but at the moment i only have 1 peripheral cable with any molex connectors, all others are SATA.  i am trying to keep the cable count down and would like to avoid purchasing any more cables. i am not worried about the PSU handling my system load but more concerned about feeding x9 molex connections through one peripheral socket on the PSU

 

if i truly need to use more than one cable to power 9 molex i can buy another, but would be less than ideal for my plans.

 

thoughts ?

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I see now, I was looking at the 750 specs which had 8x 4-pin.  Start-up current is the issue here - spinning all drives up at once when you turn the system on.  Running watts are low - 5-12W/drive and is not an issue with what you want to do.  Start-up is probably in the range of ~20W/drive for 12V, maybe ~3W for 5V.  Power up 15 drives @ 20W inrush, 25A on 12V minimum assuming the rail holds.  If voltage drops, and it will, it will be more.  The power supply can handle it, the single cable from the power supply not so well as it mainly contributes to voltage drop.  It would work if there is no current limiting per modular connector on the supply itself.  Not sure if Seasonic has current limiting on the rails per port on the modular supply or just on each rail overall.  Technically it should work as you plan with 15 drives, assuming there is no per-port current limit from the supply and you don't mind under-volting the drives on 15x spin-up.

 

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i am lacking in knowledge with PSUs but i was under the assumption that single rail PSU that all lines would be carrying be carrying full amount possible supplied instead of multi rail where Amps and such are grouped in clusters, it is this thinking that led me to thinking of using 1 socket with splitters for the 15 instead of buying 2 more psu to x3 molex cables and hooking each cage to a socket individually

also, would staggered spin-up via the controller cards have any effect or does that not affect initial power on at all ?

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One cable / connection with that many drives hanging off it is a very bad idea from the engineering standpoint and will only result in problems sooner or later.  Even if things appear to work, connections will degrade over time.  Later when multiple drives spin up (could be all of them at once) and while the server is running, you could create multiple problems with more than one drive needing to restart while the server is trying to use them. 

 

And single-rail vs multi-rail has nothing much to do with the number of connections - it is to do with the number of regulation circuits in side the supply itself.  No supply (especially single-rail types which are generally recommended for high numbers of disk drives) are able to deliver their rated current or anything close to it via only one connection without excessive voltage drops.

 

The basic question is - do you want very minimalist wiring, or a reliable server?  If you are using 5-in-3 cages, then I would try to arrange that each cage gets at least one yellow (+12v) and one black (0v) wire that runs back the the power supply (more is better) and obviously the other feeds as well - typically red (+5v), although it is the yellow and black to that do most of the work.

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I recently installed 3x 5in3 x-case cages into my server and made my own cables for them, similar to what you linked, webbing and heat shrink aswell :).

 

Each cage needs 2x molex connectors so I made 3 cables with  2 female connectors and a male connector on the end.

 

I then made up a smaller cable with a molex female one end and the correct molex connector  for my Antec modular PSU the other, this way i could reuse the small cable and just plug in any configuration of cable to it.

 

Each cage now uses a separate socket on the PSU and each line only has 2 plugs on it, nice and balanced.

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alright then, it sounds to me that having 1 wire to x3 molex split per cage is the way to go then,

i guess i will order a little more wire, thanks for the help

 

on a side note i realize that i may be leaning heavily towards minimalist wiring, but i have seen so many builds with air flow being a huge issue.  Once this gets assembled i honestly don't want to touch it for several years and i feel that with minimal wiring i can ensure i have the best cooling possible in my rig, but yes reliability trumps all which is why i am here asking folks smarter than I :)

 

I will put some photos up eventually, my Antec 900v1 has has some major work done to it, mostly in regards to cable management which this case is seriously lacking

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In your attempt to 'neaten up' the interior of your case, don't tie the SATA cables together UNLESS you have purchased shielded cables (not readily available).  Doing so can cause cross talk between the cables and lead to random read errors. 

 

Getting good air flow through a case of being sensible.  Not using too small a case and having to 'pack' things in.  Using enough exhaust /*fans with sufficient CFM to be able to move the required air flow through the case--- better to err on the high side then the low!  Blocking unused fan openings to make sure that the air flow that your exhaust fans are delivering actually contains the heat you are attempting to control.  Lastly, cleaning the inside of the case regularly to prevent the built-up of dust and dirt. 

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