Is it safe to power 12 HDD with 2 SATA power cable from PSU

[Chiyawa]

Hi,

 

I got a question. Is it safe to power 12 HDD using the included SATA Power cable from PSU? My PSU is Gigabyte G750H, and it includes 2 SATA Power cable, each with 3 connectors. I'll be using a splitter on each of the connector so each connector have 2 SATA power connector, making them 12. Is it safe to do so or will it melt the cable at full load in the long run?

 

Well, before any one asked why I don't use the peripheral Molex one, it is because all of them are occupied (2 for the ThermalTake Plus controller, 1 for 2x SAS power, and another FDD controller is for card reader with USB charging capability).

 

So far, without the 12 HDD, my system is running at a whopping ~500W (Vega 64 took 330W, CPU with 65W TDP could reach 100W if turbo'ed). PSU maximum rating for 12V rail is 748W. According to Seagate, Each HDD maximum power draw is a little over 10W, so the PSU is still capable to handle the load.

 

Regards,

Chiyawa

[Jumballi]

Is it safe? More than likely. The real question is the risk taken with each chain being affected if there’s a catastrophic failure.

[Chiyawa]

1 minute ago, Jumballi said:

Is it safe? More than likely. The real question is the risk taken with each chain being affected if there’s a catastrophic failure.

Hmm... Do you know what is the maximum current they could carry? So far to what I know, they only listed 600V, but no current rating was given.

[mahyar]

can you give us a picture of drive? from top

[nox_]

Just now, mahyar said:

can you give us a picture of drive? from top

How would that help?

[mahyar]

2 minutes ago, nox_ said:

How would that help?

to check power consumption of drives 

[nox_]

 

Just now, mahyar said:

to check power consumption of drives 

10 minutes ago, Chiyawa said:

According to Seagate, Each HDD maximum power draw is a little over 10W,

[mahyar]

if they are 10 watts each i wont recommend doing it with 2 power cables because every sata power cable can handle 50w 

[Chiyawa]

Just now, mahyar said:

can you give us a picture of drive? from top

Hmm, I don't have the picture right now, but the drive is Seagate ST2000DM008.

Here's the manual: https://www.seagate.com/www-content/product-content/barracuda-fam/barracuda-new/en-us/docs/100817550j.pdf

 

[Chiyawa]

5 minutes ago, mahyar said:

if they are 10 watts each i wont recommend doing it with 2 power cables because every sata power cable can handle 50w 

Yeah, sorry, I wrongly read.

 

According to Seagate, the startup current draw is 2A using 12V. I thought it was from 5V.

[nox_]

@JuularMaybe you or @LukeSavenije can help op?

[mahyar]

3 minutes ago, Chiyawa said:

Yeah, sorry, I wrongly read.

 

According to Seagate, the startup current draw is 2A using 12V. I thought it was from 5V.

that is 24 watts so no

[Chiyawa]

5 minutes ago, mahyar said:

that is 24 watts so no

Okay. Anyway, will it be okay if I could find a better cable?

[TomvanWijnen]

3 minutes ago, mahyar said:

that is 24 watts so no

But if SATA cables can only handle 50 when why does my PSU have a cable that splits into 3 or 4 cables? Seems like if that would immediately start burning it would be a bit odd.

[mahyar]

btw what is capacity? 

[nox_]

1 minute ago, Chiyawa said:

Okay. Anyway, will it be okay if I could find a better cable?

Please wait for people more knowledgeable in this matter to respond.

 

1 minute ago, mahyar said:

btw what is capacity? 

Again, how will this help?

[mahyar]

2 minutes ago, TomvanWijnen said:

But if SATA cables can only handle 50 when why does my PSU have a cable that splits into 3 or 4 cables? Seems like if that would immediately start burning it would be a bit odd.

3 minutes ago, Chiyawa said:

Okay. Anyway, will it be okay if I could find a better cable?

connector cant handle more than 50w if cable can you're good

[mahyar]

Just now, nox_ said:

Please wait for people more knowledgeable in this matter to respond.

 

Again, how will this help?

im checking data sheet of the drive for accurate power i need to know capacity of drive to find exact model

[nox_]

3 minutes ago, mahyar said:

im checking data sheet of the drive for accurate power i need to know capacity of drive to find exact model

21 minutes ago, Chiyawa said:

the drive is Seagate ST2000DM008.

Seagate ST2000DM008 is a 2 TB drive..

[mahyar]

1 minute ago, mahyar said:

im checking data sheet of the drive for accurate power i need to know capacity of drive to find exact model

i find the drive in the datasheet you can power two of them with two sata cables 

[mariushm]

A mechanical drive will consume around 8-10 watts , from 5v and 12v.  

It will take up to 0.5-0.8A from 5v (~4w) and up to around 0.5A on 12v (6w) 

 

Your first limitation will be the maximum output current the power supply can provide on 5v, which in your case is :

 

+3.3V 22 A

+5V 22 A

+12V 62 A

 

So assuming the motherboard and other things in your computer (usb devices, chipset, onboard sound, optical drive, whatever) needs around 4A of current on 5v (20w), this means you have at most 18 A of current on 5v.

Reserving 0.75A of current on 5V for each mechanical drive, in theory you should be able to add up to 18 / 0.75 = 24 mechanical drives. 

 

A SSD consumes less power, around 1w when idle and reading files, but during long periods of writing some SSDs can consume up to 5-8 watts, and all this is from 5v - pretty much all SATA SSDs are 5v only. So, reserve 1A for each SSD. 

 

edit: Yeah, the motor on mechanical drives will consume more current when it starts up, up to 2A or so on 12v... the 5v current will not be significantly higher. 

You have 62A on 12v, so if that's the case your 24 drives would peak at 48A of current when you turn on the PC.

 

Some motherboards and some sata controllers have staggered spinup, where they turn on each drive in sequence, waiting a few seconds between each drive. Some HBA cards have that configurable. 

Some WD drives also have that  "third 3.3v pin in sata connector is stand-by" and some controllers can hold the drive in standby using that pin and release it in sequence to reduce current at startup. 

You could in theory also program a small arduino or something to enable drives in sequence of your choice. 

 

The other limitations are:

 

* limitation of individual sata connectors : maximum 4.5A per voltage in each connector, though personally I wouldn't go above 3A on each voltage. This is not an issue as each mechanical drive consumes less than 1A, which is well below 3A or 4.5A limit. 

* limitation of connector on the power supply in which the cable with connectors goes, if the power supply is modular.  Most connectors are rated for 9A per pin, but it would probably be safe to go up to 10-12A of current.  So  basically, if you have a cable with 3-4 connectors, they could each consume up to 4.5A through each connector, but all together added up, you shouldn't go above 9A of current on any voltage. 

If we reserve 1A for each mechanical drive for each voltage, that means you should not use a single chain of connectors with more than 8-9 connectors. 

 

* limitations due to thickness of the wires used between the power supply and connectors. An AWG18 rated wire will be good for around 10-12A, if the distance is short (let's say 1-2 meters of cable between psu and last connector)... so this is not an issue, the connector on the psu will be rated for less current. 

 

An AWG20 wire (more common in very cheap power supplies) will only be recommended to be used up to around 8A of current. 

 

The longer the wire between the psu and connector is the more losses will be in the cable, which are proportional with current. The formula is  Voltage loss = Current x Resistance

On AWG18 wires, the resistance of the wire is around 0.021 ohm per meter, so if you have a cable that's 1 meter long between psu and last connector this means there's 2 meters of wire between that hard drive at the end of the cable and your power supply. 

If you have 6 hard drives and each consumes 1 A of current, that means the last drive will see a voltage loss of V = 6A x 0.02 ohm x 2 meters  = 0.24 volts. 

So if the power supply outputs 12v, the last hard drive will see 11.76v.  If the power supply outputs 5v, the drive will see 4.76v 

This is the reason modular cables will NOT have 9-10 sata connectors, because all those add up and you get to high current per chain of connectors. 

In most use cases where there's only 2-3 sata drives per chain, so around 2A of current, and with smaller length of wire, the voltage drop is low enough that it can be ignored. 

 

You can also use those adapter cables which convert one molex cable to 2 x sata connectors if you want to add more drives. 

Each molex connector is good for 5A of current, so up to 5A can go to 2 drives which would never consume that much current so it's all good. 

But if you go this route really really make an effort to buy adapters that have crimped pins, not molded SATA connectors (basically the kind where you could pull out the pins from inside the SATA connectors).  They're a bit more expensive but much safer and more reliable. 

 

[MojaveTM06]

I think you could get away with this for a long while. But I wouldn't do this myself because if one of the cables broke, you could lose 6 drives if you are unlucky. Although Maybe you can get away with it. Goodluck to you.