Power Supply Cables

[TwistedJack]

Just a quick question, 

 

The power supply comes with a definite number of sata connectors, so if I want to increase the number of hard drives in my pc, won't I have a deficit in the number of power connectors? 

[MkaiL]

Those cables usually have 3 or 4 sata power connectors on each cable. That should be enough, how many connectors do you need?

[Guest]

Bitfenix do Molex to 4 x SATA power cables if you did run short.

[mariushm]

A power supply is not aware of what connectors are used on the cables, the power supply simply outputs a certain amount of power on three main voltages: 3.3v , 5v and 12v

 

The number of actual sata connectors or molex connectors (the old hdd ones) varies from power supply to power supply, from model to model .. it's a simple way to create artificial differences between two models in a power supply series for example.

Up to a point, you can use molex to sata adapters which convert one molex connector into 1 to 4 sata power connectors, or even sata to 1-3 sata connector adapters, in order to have more connectors.

 

You're only limited by the current the power supply can provide.  For example, a regular mechanical hdd may consume 0.8A from 5v and 0.6A from 12v  but you have a power supply which can generate 25A on 5v and 50A on 12v (typical for a 550-650w rated power supply)

Leaving aside 5A of current on 5v for motherboard and other things, you're left with 20A of current on 5v available for hard drives, which means you could in theory install up to 20A / 0.8A = 25 hard drives. Those 25 hard drives would use 25 x 0.6 = 15A from 12v, leaving 25A to power processors and video cards.

In reality, it wouldn't be a good idea to connect more than 15-20 hard drives to a single power supply.

 

I'm saying up to a point a paragraph above because it's not actually a good idea to create long strips of sata connectors, because you're limited by the thickness of the cables that come from the power supply to the connectors ... basically the thickness determines how much current can be sent through those cables to the sata connectors - for standard AWG18 cables, the maximum current is about 10A on each wire (so if a single hard drive uses up to 1A from power supply, then the cable thinkness limits you to about 8-10 sata connectors on a strip of connectors coming from the power supply. 

Power supply manufacturers use strips of maximum 3-4 connectors to allow each hard drive to use more current if they need to.