SATA power connector

[rivan]

What's the advantage to SATA power connectors on hard drives over the standard 4-pin molex? What're all the extra pins for?

 

[Roguestar]

http://en.wikipedia.org/wiki/SATA#Cables_and_Connectors

Edit: Now even more refreshing with added anchor tag! Also available in strawberry.

 

[corkyg]

The short answer is, the SATA power cables provide additional voltage needed to make the devices hot pluggable. the 4-pin Molex connectors do not provide 3.3 V power, these adapters provide only 5 V and 12 V power and leave the 3.3 V lines disconnected. Without 3.3 V power, the SATA device may not be hot pluggable.

 

[Roguestar]

It'll still work, though, which is a relief for those who want to buy SATA drives but not have to change their PSU. Hooray for backwards compatibility even if it sometimes stops us adopting new standards completely.

 

[Zepper]

3.3 V has nothing to do with hot-swapping but the SATA power connector does as for hot plugging it is very important that the ground lines connect before the hot lines and disconnect last...

Newer electronic devices (ICs and LSICs) are capable of running off 3.3V. The specs writers were assuming that 3.3V devices would be used increasingly thus affording a power savings. At least to this point, most 3.3V devices won't be overloaded on 5V so it is easier for the drive makers to produce PCBs with just one Vcc bus, so the 3.3V lines haven't been used that much yet. Most SATA drives still provide both types of connectors. And those that don't will run just fine with an adapter to the old style connector which only offers the two normal voltages anyway.

.bh.

 

[rivan]

So if I use the SATA connector, will the same drive consume less power? I'm too much an electrical n00b to make an educated guess, but that seems counter-intuitive to me.

 

[StopSign]

No it won't. The spindle doesn't run on the 3.3v.

 

[Zepper]

No the power usage for desktop drives (3.5", 7200 RPM) has been the same for the past several years whether SATA or PATA: ~2 Amps (@+12V) max starting and ~1.5A running for the motors and 1Amp max (@+5V) startup for the logic circuitry. Check the spec sheets at the mfr's web sites for the drives you are interested in for accurate numbers.
. When they finally go to using 3.3V only for the logic circuitry board the power usage should drop a bit - from about 5W now to about 3.3W then. I think a breakthru of some magnitude in the materials or drive technology used in the platters and motors would have to occur before the 12V power usage will drop much. Perpendicular recording could contribute to that as you need just half the platters for an equivalent capacity drive. I haven't compared the power specs on the Seagate 7200.10 P-R drives with the 7200.9 series - something to do when there's nothing else...

..bh.