Dangers of using external power source with internal hard drive
2014-07
Richard
Is it okay to connect a internal hard drive (IDE/SATA/SCSI) to an internal controller (e.g. on-board the motherboard) and supply the power via another power supply or an external unit like the one below:
Does it matter if the external power supply is grounded or not?
EDIT: I'm aware the power supply below is grounded. If both the computer's PSU and the external adapter are grounded to earth, I assume there wouldn't be any problems. The one I have isn't. I'm afraid that the floating ground might cause problems. Any ideas?
mvp
SATA and SCSI are using low voltage differential signaling for data transmission, which means they should tolerate even high ground offsets. IDE/PATA doesn't use this, so it should be much more sensitive to bad ground.
That said, I would avoid doing this, or at least make sure everything is properly grounded.
Wes Sayeed
It's perfectly fine. I have a power brick just like that. Hard drives are not "smart" about their power. There is no communication between the hard drive and the power supply. Electricity is electricity in that regard.
There are legitimate concerns about "dirty" power. But there is nothing saying that a computer's power supply is inherently better or safer than the external brick you linked to. It's just more complex is all. The item in the picture you linked to is grounded. You can tell because of the three blades in the power connector that goes to the wall.
The only concern you need to worry about is making sure the drive is powered up before you turn the computer on. SATA drives support hot-plugging but some BIOSes do not. IDE does not support hot-plugging at all. You won't harm the drive or anything. It just may not work.
Tanj
Would there be any problem connecting an internal SATA drive using an old PC Power Supply for its power and connecting to an external SATA port on a laptop? Would there be any voltage conflicts?
I just had a motherboard die and need to get some data off the hard drive. I don't have another computer that I could just drop the drive into, but my laptop has an external sata port.
8088
The easiest would be to buy or found an IDE/Sata to USB cable. They are plenty of them at various prices, I bought one for cheap on eBay. They usually come with an external power supply (with a Molex plug and a Molex-to-SATA-power adapter).
Here is an example:
Even without this and if you can use your power supply to deliver voltage to the SATA drive, I suppose your laptop has a eSATA port, not a SATA port. You'll also need a eSATA-to-SATA cable then.
8088
The safest way is to get an external enclosure.
If you're going to use the old power supply, make sure the power supply and the laptop are plugged into the same wall outlet/power strip -- this ensures they have a common ground.
Do not leave the laptop running on battery power.
As Chris mentioned, the old AT style power supplies have a manual power switch, but no SATA power connectors. You'll need a Molex-to-SATA-power adapter to power the drive.
If your power supply is an ATX/ATX-2, it won't power on by itself. Normally, the power-on signal comes through the motherboard's main power connector when you hit the power button on an ATX system. You can force the power on by connecting pin 14 (PS_ON) to one of the GND pins (13 or 15, for example). (Diagram source and more info)
Be very careful when using an ATX power supply in this fashion. This is meant for testing a PSU, not extended operation.
Chris
If it is an ATX power supply then it will not automatically turn on to power that hard drive. If it is an AT power supply with the manual power switch, then it will not have SATA power connectors.