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Power 7 hd's off 1 string from PSU?

D

DisgruntledVirus

Lifer
The thought occurred to me this morning to mod my server a bit. I'm not thrilled with how it looks right now inside (although it's not too bad), namely the HD's SATA power that I want to change. I have a modular PSU (NZXT Hale 650W) powering it, and I want to know if it's possible to take 3 of the connectors off one string and put them on the other so one string can power 7 HD's. I don't want to kill the PSU or drives by doing this though.

Anybody know if I can do this? I can post pics of what I intend to do if it helps.

UPDATE: When I posted the OP I forgot that I was currently using 1x3 and 1x4 splitters off one string of molex connectors from the PSU to power all the drives (plus 2 fans on that same circuit). When I realized that I went ahead and just spliced the connectors onto the cable. It works fine. It's for a server that's up 24/7 so drive power up draws rarely matter and it's very rare all drives will be hit at the same time.

So, yes you can do it without issues.
 
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I am not convinced that a single SATA power cable is able to power 7 HDD. It may power it but I think the wires might burn out from the power those HDDs draw from a single cable. The PSU might not be harmed but the SATA power cable will.
 
dma0991 said:
I am not convinced that a single SATA power cable is able to power 7 HDD. It may power it but I think the wires might burn out from the power those HDDs draw from a single cable. The PSU might not be harmed but the SATA power cable will.
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You don't think a single SATA power cable can handle 120 watts maximum?
Do you have any reasoning for this?
 
Soundmanred said:
You don't think a single SATA power cable can handle 120 watts maximum?
Do you have any reasoning for this?
Click to expand...

So do you have experience chaining 7 SATA connectors to 1 SATA cable? I am just saying that the cable gauge might not be able to handle it.
 
dma0991 said:
So do you have experience chaining 7 SATA connectors to 1 SATA cable? I am just saying that the cable gauge might not be able to handle it.
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Well, it would mean adding 3 power connectors to it. The string has 4 on it already. It's the same gauge as the Corsair HX flat ribbon style cables.
 
DisgruntledVirus said:
Well, it would mean adding 3 power connectors to it. The string has 4 on it already. It's the same gauge as the Corsair HX flat ribbon style cables.
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Well if Soundmanred is convinced that the SATA power cable is capable of handling 7 HDD I don't see the harm in trying it out. I'd like to believe manufacturers places 3-4 SATA connectors on a single SATA cable for a reason.
 
dma0991 said:
Well if Soundmanred is convinced that the SATA power cable is capable of handling 7 HDD I don't see the harm in trying it out. I'd like to believe manufacturers places 3-4 SATA connectors on a single SATA cable for a reason.
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Because most people dont need more than 3-4 at a time? 😛
 
DisgruntledVirus said:
Because most people dont need more than 3-4 at a time? 😛
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Hmm never thought of that but I currently have 3 HDDs and growing at a very fast rate :awe:. It's nice however to have the SATA connectors that are detachable. Had that on my Delta OEM unit but the current PSU that I am using does not have them. If it had them I would have rearranged their position to get a cleaner look.
 
dma0991 said:
Hmm never thought of that but I currently have 3 HDDs and growing at a very fast rate :awe:. It's nice however to have the SATA connectors that are detachable. Had that on my Delta OEM unit but the current PSU that I am using does not have them. If it had them I would have rearranged their position to get a cleaner look.
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Yeah I rearranged my Corsair in my gaming rig, and plan to do it with my server rig. I just would like to use 1 cable to power all of them instead of 2 if possible.

Would be a lot cleaner looking 🙂
 
I don't understand why someone would think that a cable of the same gauge would power a single item with 150 watts (or even twice that), but not seven just because there are more connectors.
It may not "sound like a good idea", but logically it doesn't make sense to think it can't.
The number of connectors, like another poster said, is due to users rarely needing more than a few connectors on a cable, not because of the actual capacity of the cable.
I have ten HDDs in my system (6x 2TB, 4x 1.5TB), with two power cables, each one powering 5 drives.
(I bought extra SATA power connectors from FrozenCPU.com, if you need to get some)
Luckily my power supply is modular so I didn't have to work on the cables while sitting next to my case or removing the power supply. 🙂
 
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I'm not sure why the cable is being questioned really. Find out the gauge of the wire on the jacket, find out how many amps it'll carry and look up the rated amperage for that size wire.
 
rstrohkirch said:
I'm not sure why the cable is being questioned really. Find out the gauge of the wire on the jacket, find out how many amps it'll carry and look up the rated amperage for that size wire.
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Because I don't have any way to measure it here 😛

So basically find out gauge of wire, look up it's amperage rating, then see what the HD's draw and multiply by 7. If HD's x 7 < rated cable amps I'm good right?
 
There's a voltage drop after every connector, isn't there? At least the playtool.com site said something about this.

I think it's a bad idea personally, but then again, it's not that much worse in theory than using molex splitters to power more devices off of a strand, and I do that without worry, so I guess you would be alright.
 
Yes I have had burnt wires before but that is not related to PSUs. It was more of an experiment and ran too high of a current on a thin wire, much thinner than the 18AWG most standards PSUs uses.

Still, I see no harm in OP trying it out. It is a modular cable and if something goes wrong a replacement to the original with 3-4 SATA connectors can easily be bought unlike non modular PSU.
 
Well wait... I just realized something.

I have all 7 running off one cable using 1 molex to 3 SATA+1 molex to 4 SATA. All 7 drives are off one cable from the PSU though... So there shouldn't be any issue then right?
 
Sadly I dont remember this aspect of my electrical engineering studies in 1990-91, but I remember there is a formula. That if you know the cross section area of the cable, and the material it is made of (copper, aluminum etc.), you can calculate how many ampere it can withstand. Then you can easily use P (Watts) = U (voltage) * I (Current), to find out the maximum watt that cable can sustain. Find the rating in watts for peak load of your harddrives, and compare it to your calculation in order to find out how many drives you can use on that particular cable.
 
What about the wiring inside the PSU can that handle the extra load? Will that heat up?

I would not even think about the exterior wiring until I thought of the interior wiring.
 
Soundmanred said:
If they're technically all on one cable now, then there's your answer.
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Yeah, I redid it about 2 hours ago and have it up and running again. No issues so far.

I completely forgot that they were already all being ran off one string of cable. It's much cleaner looking now though IMO.

thescreensavers said:
What about the wiring inside the PSU can that handle the extra load? Will that heat up?

I would not even think about the exterior wiring until I thought of the interior wiring.
Click to expand...

First, it's been running all off one connection in the PSU for ~3 weeks now 24/7 fine. Second it's a 80+ Gold rated high quality PSU. If it was an OEM deal, I might be worried but I'm not at all worried with this PSU.
 
I tried to string 5 2TB drives off a single modular cable and had trouble when they were spinning up. I split them over two modular cables and had no more problems. I was using a 500W OCZ modular power supply.
 
I have a WD Blue 500GB. The specs says it uses .68A for 5Vdc and .55A for 12Vdc. That's 10W max. 10W x 7 = 70W. I'm pretty sure a single SATA power cable can handle that.

The only thing I would be worried about is spinning up all 7 of them during boot, but I wouldn't expect the wires to get hot enough to start melting/burning.
 
There are a lot of things you have to consider.
The total number of amps for the drives. Drives typically draw .5 A on 12V and 1A on 5V. That is a high value you can use.
7 HD = 3.5A on 12VDC and 7A on 5VDC

Most PSU have wire gauge large enough to handle that load as long as you keep the wire length under 3 feet. Longer lengths will have a higher voltage drop but even that isn't too big a deal. No hard drive uses 5 or 12 vdc directly. They use dc - dc converters to step down the voltage to 3.3 and 1.8vdc at higher currents. One issue you can run into is some PSU take a second or two to stabilize the voltages at power on. If something pulls a large amount of current on one rail before that voltage stabilizes then it can cause the power supply to see too low a voltage causing a error inside the comparator and the supply assuming something is broken and going into protect mode. The simplest way around this is adding a delay to the drive power on. If the bios doesn't support it then wiring a toggle switch to the drive power that can be flipped after main power is on will do the job or a more exotic approach is to use a timer circuit with a relay, cost about $5 in parts to implement.
 
Well, just for fun I got out some splitters last night and hooked all 10 drives to a single cable from the PSU and it worked fine. I powered the system on and off a few times, and accessed them all at nearly the same time. My PSU did not explode, nor did the wires melt into pools in my case.
 
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