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My problem is thus: I have an old SATA drive I want to retrieve data from, but the only desktop I have left working in the house doesn't have SATA connectors from the PSU, but does support SATA on the motherboard.

I do own a PSU which has SATA connectors, so I'm wondering: can I connect my second (SATA-capable) PSU to the hard drive and then connect that hard drive to the original computer with it's own PSU without any issues?

I am aware I could buy a molex convertor but I'd rather not if this solution works since I only need it connected for a short period to retrieve some old files.

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migrated from electronics.stackexchange.com Jul 31 '11 at 17:18

2 Answers

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IF you mean you want to use only the second PSU you have to power up your SATA HDD, then you have to separately turn it on. You can do it by shorting the green wire to any black wire of the 20 or 24 pin (which one you have). see this link :

turn on PSU without mainboard

Please note that powering on a PSU without load can be dangerous to PSU, AFAIK.

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I can actually power up the other computer (it just freezes, some unfixed issues) normally so can I effectively put the two desktops next to each other and use the powered cable from one into a HDD in the other? – Owen Jul 31 '11 at 13:43
@Owen yeah you can do that, it doesn't matter. your PSU does only supply power to components and does not care about the data part. – Sean87 Jul 31 '11 at 13:46
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The only issue is the grounding, there will be two potential reference grounds as you will be getting a ground from external PSU and another ground from your PC.

One easy option would be powering your PC from the external PSU.

The other option would be tying the grounds of external PSU and internal PSU and check the current flow on that cable. If there is no decent current flow, you can execute your plan. If there is current flow, you will be subjecting your HDD to the similar current flow. If it is 1-2mA probably be ok, but if it is more than that I wouldn't risk it.

But if you decide to risk it, several things could happen. Your disk may burn, or rather the controller inside. Your disk may be operational but you may not fetch the data, the shift in ground may make the controller interpret the data wrongly. I assume SATA protocol would take care of these problems so you would be ok.

Disclaimer: I take no responsibility whatsoever with respect to your system and don't claim this info is reliable or accurate.

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As long as both power supplies are connected via the ground-prong to a true earth ground, the ground difference between the two on the low-voltage side should be negligible to zero. Even just having them plugged in to the same power strip (if the house doesn't provide ground wiring) should mitigate this issue. – jcrawfordor Aug 1 '11 at 2:29

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