basically I'd like to connect a 3.5" SATA drive to the place were a 2.5" SATA drive would be in my laptop.

Here's a picture showing both kinds of drives by Dsimic:

2.5-inch SATA drive on top of a 3.5-inch SATA drive, close-up of data and power connectors

I have been reading up on SATA connectors and apparently only the left side of it is being used for data, the right one is for power as the following diagram shows:

SATA Power connector

Since my 3.5" also has a PATA power connector (the one on the left, uses one of those Molex cables. Would it be possible to connect the big disk to the laptop somehow? Maybe using a Molex cable to provide the drive with a 12V source and enough power, and a regular SATA data cable for the connection?

NOTE: This question could be related to this one but I think it goes its boundaries.

  • 1
    Those are the same SATA connectors for power and data. You can just plug in the cables and go. The only thing I don't understand is, how are you going to fit a 3.5" drive in your laptop? – DrZoo Feb 6 '18 at 17:37
  • Sure, the data/control and power connectors are the same and will fit, but the connection of a 3.5' HDD to a laptop may not work. Since 2.5" HDDs do not use +12VDC, the laptop power connector is likely to not have that voltage. Regardless, the laptop is not expecting the ampere demand of a 3.5" HDD, and probably cannot supply that much current. – sawdust Feb 6 '18 at 20:07
  • @DrZoo, It's an old-ish drive I had around and I'd like to assess its health somewhat through SMART data. But I don't have access to any hardware to work with it right now, and from what I've read it seems to be hit or miss with external enclosures exposing SMART through USB. That's why I thought of maybe connecting it temporarily to the SATA port of my laptop. – James Russell Feb 7 '18 at 14:03
  • That's what I fear @sawdust, but we'll know soon enough, I've just ordered a couple of SATA cables to try it out ;). – James Russell Feb 7 '18 at 14:06

Yes, the connectors are identical.

A rule of thumb, if they would have been different, it would simply have a different shape to make sure it would not work. This is something that wasn't always the case, but for the past, I dunno... 10 years, in ICT, connectors that fit can be used without causing any form of damage.

The only exception here is USB-C. It will work, but USB-C can have additional protocols, so if a cable does not support that protocol some features may not work. But SATA connectors, both power and data have this rule: if it fits it'll work.

  • Yes, the connectors are the same and it should work. The problem, however, is using it instead of a 2.5" drive in a laptop (won't fit). So, I think, the main question is can it be used externally with a standard desktop SATA (data) cable and an external power supply? – user772515 Feb 6 '18 at 18:20
  • 1
    Yes, that would just work. But a PSU might not be entirely trivial, e.g. a regular PC PSU will not power on unless there is enough load. And it might be so much easier to use an external dock with a eSATA or USB port. – Hennes Feb 6 '18 at 18:51
  • 1
    A laptop will still power 12 volts to the drive, similarly to a PSU in a PC, so it doesn't matter. Yes, the drive won't fit, but OP may simply just want to quickly test a laptop suspecting a faulty drive and swapping it for a 3.5" drive just once leaving it outside of the laptop during testing. – LPChip Feb 6 '18 at 19:01
  • @LPChip I previously tried to connect a 3.5" SATA drive to my laptop (HP Probook 6550B) through a SATA extension cable and it would not work. I had to modify the extension cable to connect an external PSU. (Full info in my post below). – Bja Jan 14 at 16:24
  • I highly doubt that a laptop will still provide 12V to an internal 2.5" SATA drive when all SATA 2.5" drives (including 2.5" SSD) all use 5V and not 12V. There is no reason to have extra circuitry and drain on the battery when nothing is going to use it. – Bja Jan 15 at 4:14

For any future readers (May not be possible for everyone, but I was desperate and had the parts laying around, including soldering iron and the necessary skills):

When my laptop 2.5" SATA drive was failing I cloned it onto a 3.5" SATA drive I had spare.

I tried the SATA extension (See pictured lower) plugged into the 3.5" SATA drive and the laptop but it would not work.

I then proceeded to unplug the extension cable and cut the four power wires in half (two black, red and yellow wire) while leaving data intact.

After cut I wrapped the four wires from the laptop end in electrical tape (individually wrapped, then wrapped together), and soldered a Male Molex connector I had laying around (cut from something old before throwing away, probably cheap case fan) on the other 4 wires (making sure I got the pins correct (red to red, yellow to yellow and so on)).

After the SATA extension cable had a Molex connector fitted onto it I plugged the SATA extension cable into both the laptop and the 3.5" SATA drive.

I then plugged the Molex connector into a spare PC power supply (internal supply not in use), along with a PSU tester (See pictured) plugged into the main PSU ATX motherboard connector (Same can be achieved by joining ATX motherboard connector pin 16 and pin 15, More info on wikipedia See "Power On" pin in Wikipedia Table).

After that was all done I started the laptop and continued to use it as a temporary desktop (since setup wasn't portable).

After turning off the laptop I unplugged the PSU tester to turn off the PC power supply powering the 3.5" SATA drive.

Note: while this setup worked for me, I will not be responsible if you put the Molex plug on incorrectly and blow up the drive. So be careful and triple check your connections.

Also note My laptop still works and is still my primary computer, so it doesn't provide enough power through the SATA port even when the laptop is plugged in using it's power pack.

Quoted from Someone at whirlpool

You can't put a 3.5" SATA drive into a laptop because, even if it could physically fit in, the laptop probably doesn't deliver 12V to the appropriate pin in the SATA power connector, but there's no reason you can't use a 2.5" SATA drive in a desktop.

SATA Extension cable PSU Tester

  • A 3.5" drive requires more power, than a 2.5" drive, normally the laptop should be able to provide this power, but given that your laptop was already failing, it may have been failing for the same reason as why you had to connect additoinal supplies. Normally, a 3.5" drive should be powereable by the cable. – LPChip Jan 14 at 16:46
  • @LPChip I think you misunderstand, The laptop works fine and this was 2 years ago (it still works), it was the 2.5" SATA drive that was failing, but even with the laptop power supply connected it would not power the 3.5" drive. This was also an HP business laptop (HP Probook 6550B) not a cheap consumer level laptop. After my replacement 2.5" SATA drive arrived I cloned the 3.5" drive to the new 2.5" drive and continued using the laptop and still do to this day. – Bja Jan 14 at 16:58

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