How many drives on one power cable?


page3

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Hi all,

 

I’ve recently built my first UnRAID server, which went well but I have question regarding how I’ve powered the hard drives. Better safe than sorry, so though I’d ask here.

 

My build uses the Corsair SF450 Platinum PSU. I want to power 6 x SATA (at least for now).

 

I have the SATA power from the PSU connected to four drives using the included cable. Additionally I have 2 x 2 way SATA splitter on two of the connectors in order to give me a total of 6.

 

There are no further SATA power sockets on the PSU.

 

I also have the Molex socket being used via the supplied Molex cable only to the case fan. This cable has a spare a Molex socket which I could use to go to two of the drives using something like the Silverstone Molex to 4 SATA sleeved high-quality cable. 
 

To summarise:

 

Now:

PSU -> Sata -> Sata (split to 2 Sata) -> Sata -> Sata (split to 2 x Sata)

 

Possible:

PSU -> Sata -> Sata -> Sata -> Sata

PSU -> Molex -> Molex -> Sata -> Sata

 

Would this be a safer bet?

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On 1/7/2020 at 3:14 PM, page3 said:

Would this be a safer bet?

Yes. The more wire you can feed to your drives, the better. Trying to feed all the drives through 1 lead is possibly going to cause voltage sags when all drives are asked to spin up at once, for example when you tell the server to shut down after it's been dormant with all drives spun down, or a scheduled parity check.

 

If possible, also limit the number of splitters, each one is another point of failure. If this model of PSU is modular, I'd recommend contacting the manufacturer to see about getting more cables with SATA power, so you can eliminate all splitters and adapters.

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I am considering the same PSU. It is modular with two sockets for "peripheral & SATA". (4xSATA and 3xMolex)

 

Assuming you are using 3,5" HDDs then the general rule of thumb is that a SATA plug can power two drives, Molex can power four. (use crimped and not molded connectors. 🔥 ) SSDs and 2,5" demand much less power.

So your solution would be within specs.

Adaptering from Molex would be somewhat safer and distributes the load better. The Cable run may be more akward.

 

Corsair it self only offers Cables with 4 SATA connections it seems (like supplied).

https://www.corsair.com/eu/en/Categories/Products/Accessories-|-Parts/c/Cor_Products_Accessories_Parts?q=%3Afeatured%3AproductCategories%3ACor_Products_Accessories_Parts_PCComponents_PowerSupplies%3AaccessoryType%3ASerial%2BATA%2B%28SATA%29%2Bcable&text=&pageSize=12#rotatingText

Maybe there is something aftermarket.

 

If you find a different solution for your fans, you could get another PSU->4xSATA cable, so 8xSATA but no Molex. This means your HDDs would not be on an adapter at all, so this would be the most reliable solution.

Fans often only use 12 Volts and less power than a HDD. Also voltage fluctuations or drops will not matter that much to them. So "back-adaptering" from SATA-to-Molex-to-Fan or sodomizing a spare 12V-CPU 4-Pin from the PSU may be an option.   

 

You mentioned 6 Drives for now - maybe consider how likely this will change and what your upgrade path would be then.

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On 1/9/2020 at 9:09 PM, TobiRh said:

Molex can power four. (use crimped and not molded connectors.

Can you please link to someplace we can get such cables? Just spent forever searching amazon and it's hard to tell which ones are safe.

 

*and is it safe to use these molex->sata adapters on ssds? I heard you lose the 3.3v pin (which some ssds use?)...

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40 minutes ago, unraidun said:

Can you please link to someplace we can get such cables? Just spent forever searching amazon and it's hard to tell which ones are safe.

 

*and is it safe to use these molex->sata adapters on ssds? I heard you lose the 3.3v pin (which some ssds use?)...

https://www.amazon.com/Monoprice-108794-24-Inch-15-Pin-Female/dp/B009GULFJ0

https://forums.tomshardware.com/threads/ssd-power-is-it-using-3-3v-or-not.659059/

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Cool thanks so if I'm reading that article right, only the 1.8" ssds use the 3.3v? So for your typical 2.5", these molex->sata adapters will work just fine?

 

And those adapters look perfect for my needs. The molex cable off my Corsair 750m has 4 plugs on it, so can I use TWO of those sata adapters (same line, but in two separate molex ports), for a total of 8x 5400rpm drives? They will be the only devices on that one dedicated line.

Edited by unraidun
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22 minutes ago, unraidun said:

They will be the only devices on that one dedicated line.

It would be better if you could power each string with a separate line so you would only have 4 drives per PSU lead, but it would probably be OK, assuming the PSU has good regulation. The more wires from the PSU you can use, the better.

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Unfortunately I only have 2 molex cables for my modular ps (Corsair 750 CX M). I couldn't find anyplace that sells extras/replacements, or I would happily run 3 lines instead of just two. But do you think my Corsair has "good enough regulation"?

 

*btw, how can you tell those sata adapters are the good 'won't catch on fire' kind? Is there something special about the shielding or how they are threaded through the connectors?

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32 minutes ago, unraidun said:

But do you think my Corsair has "good enough regulation"?

Probably. Hard to tell without putting a scope on the output as all the drives are spun up.

 

33 minutes ago, unraidun said:

how can you tell those sata adapters are the good 'won't catch on fire' kind?

google sata idc

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Cool thanks again!

 

Just ordered two of those adapters (I will play it safe, and start with just 4 drives on each line, 8 total). Maybe by the time I get a 9th drive I will have purchased another modular ps I can steal a molex from...

 

** Oh wait! All this time I had been searching for a SATA extra/replacement cable for my modular ps, I just searched for Molex and this came up...

 

https://www.amazon.com/COMeap-Corsair-Modular-Supply-Adapter/dp/B07GRM7MRD/ref=sr_1_1?keywords=molex+modular+power+supply&qid=1578889107&s=electronics&sr=1-1

 

The pictures look kinda scary ("if you use other brand psu's it will burn..."), but they explicitly mentioned my corsair cx as being supported...

 

So just get one of these + one of those 4 way sata adapters (for every 4 drives), and I am golden, right?

 

Edited by unraidun
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Looks good to me. Ideally you wouldn't use any adapters / extenders, but if you must, a high quality 4 pin connector is the best way to do it. SATA connectors aren't designed particularly well. Splicing and soldering the adapters in place, or just building your own custom cables is the best solution.

 

To ensure you are getting the correct cables, visually trace each pin position from end to end. The all black wires make it a little tough, but it's still doable with patience. Compare the stock cables with the ones you order, and make sure all pins are connected the same way. If you have a multimeter to test continuity, even better, or if you really want a confidence check, get a power supply tester that measures voltage on the 4 pin drive connection.

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Was about to order two of those COMeap 6pin -> Molex ps cords, and I saw they DO make sata versions (which also claim to be compatible with my Corsair ps)...

 

https://www.amazon.com/COMeap-Adapter-Corsair-Modular-Supply/dp/B0823989PS/ref=sr_1_6_sspa?keywords=comeap+corsair+6+pin+sata&qid=1578972588&s=electronics&sr=1-6-spons&psc=1&spLa=ZW5jcnlwdGVkUXVhbGlmaWVyPUFXSEMxWFROWERHJmVuY3J5cHRlZElkPUEwNTAxMzM5VDFUUVAzUUxFNDk0JmVuY3J5cHRlZEFkSWQ9QTAzNDI1NDFPRTZQMUZUTTRNMUwmd2lkZ2V0TmFtZT1zcF9idGYmYWN0aW9uPWNsaWNrUmVkaXJlY3QmZG9Ob3RMb2dDbGljaz10cnVl

 

So I COULD in theory power everything with pure sata (no molex -> sata adapters), but then my cables won't be long enough to reach the farthest drive bay. My case seems like it's pretty common server dimensions (Rosewill L4500 server chasis).

 

How in the heck do you guys power your far corner drives WITHOUT resorting to daisy chaining/adapters? Would tacking on a simple male->female 3 inch sata extension cable to each port be better/safer than the previous plan (molex->sata)?

 

*sorry didn't mean to hijack this thread, started a new thread regarding this issue/sata port fires...

 

 

Edited by unraidun
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  • 1 month later...

Just to add to this post, i have been using (unraid) x7 4tb drives and x1 6tb (parity) for a total of 8 drives with same molex power cable with the Corsair CX430M w/o any issues. I'm using the Rosewill RSV-L4412 - 4U so x2 4pin molex feed 4HD and a fan and i've been adding drives w/o opening the case till now that i bought another 4tb drive and didn't have a way to feed it. I felt sorry for my PSU.

 

I'm buying the 6 pin male to 4 pin molex female shown above and split the number of HD between them.  So for now it'll be 6 and 3 until i max out my case capacity to 12 HD, 6/6 per connector. By then i might already upgraded my PSU to a Corsair TX850 i got laying around.

 

Thanks for all the info and help.

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