Internal SATA power connectors on Intel boards

[rafett]

Hi all,

I'm looking to build a low power home server; mainly for files and as an internet gateway. It's going to be on 24/7 and running mostly idle.

Both the DN2800MT and DH61AG Intel motherboards look like good starting points. They both take an external DC power supply and provide on board SATA power points. However the technical documentation (http://downloadmirror.intel.com/20068/e ... Spec05.pdf) states:

Code: Select all

Board power supplied through SATA power connector is rated at a maximum of: 
* 1.0 A from 12 V rail 
* 2.5 A from 5 V rail 
* 0.5 A from 3.3 V rail

Now most 3.5" HDDs appear to require a lot more than 1A on the 12V rail (WD Green drives for example tend to run around 1.7A http://www.wdc.com/wdproducts/library/S ... 701229.pdf).

Does any one have experience running 3.5" HDDs on these motherboards? Are they at all compatible or would I be limited to 2.5" drives?

If the motherboards are not compatible are there any external power supplies that could provide both SATA power and the 2 pin 19V MOLNEX that these boards take?

Thanks for all your help!

[HFat]

Does any one have experience running 3.5" HDDs on these motherboards? Are they at all compatible or would I be limited to 2.5" drives?

I tried booting a DN2800MT with a 3.5'' 7200rpm single-platter and it worked. But it was only a quick test. I can't say if it would work reliably and of course I can't say if it would work with all drives and with all boards. My guess would be that these boards can power some drives regardless of the specs, but not all drives.

[washu]

That spec of 1.7 A is peak power, not average. All mechanical HDs need more power at spinup, but it is very brief. I don't know what the peak power capacity of those Intel boards are, but it likely can withstand 1.7 A or more for the duration of drive spinup.

If WD greens drew 1.7 A average that would be 20.4 W on just the 12 V rail alone. We know from this site and others that they draw much less most of the time. From the spec sheet the average power is 6 W or less, or 0.5 A if all the power was on 12 V. Assuming that the board can stand the spinup peak, two WD greens is not unreasonable.

[rafett]

Thanks for the advice. Doing a little more research I see that Seagate Barracuda drives need almost 2A to spin up and Deskstars about 1.5A.

I'm not sure about the long term reliability of flashing almost double the rated current through motherboard internals so I think it's probably best to use another MB if using higher rated drives.

[HFat]

Seagate Barracuda drives need almost 2A to spin up and Deskstars about 1.5A.

This can't be true. Different models will not require the same amount of power. Maybe that's the value for the most power-hungry models in the last generation of Barracudas and Deskstars.

Barracudas and Deskstars aren't low-power drives by the way. Other lines should require less power to spin-up.

[rafett]

This can't be true. Different models will not require the same amount of power. Maybe that's the value for the most power-hungry models in the last generation of Barracudas and Deskstars.

I realize that these 3.5" drives aren't really low power, but they do seem to be representative of what is available.

Seagate 3.5 drives are all Barracudas (desktop) or Constellation ES (server). The latest gen Barracuda specifies 2A spin up (manual) and the Constellation 2.05A (manual),

The "low power" 5400RPM Deskstar 5K3000 specifies 2.0A as well (datasheet).

Samsung drives seemed to have ceased to exist since Seagate makes them now but the Spinpoint needs 2.2A (manual).

There do not seem to be that many options in the 3.5 consumer SATA drives market. It's WD, Seagate or Hitachi. And they all draw above 1A on spin up.

Since 2.5" drives only draw on the 5V line, and the motherboards are rated 2.5A on that it makes me wonder just what they had in mind when they only provided a 1A 12V line.

[HFat]

The spec sheet doesn't trump the fact that that more platters you've got, the more power you need to spin the up.

I don't know what they meant what line for. I don't know what drive pulls how much from which line. All I know is that my DN2800MT powered a Barracuda.