Molex to SATA power adapter

[ArisVer]

I am using a molex to SATA cable adapter for my main disk which has the OS, a Crucial M500. Are there any drawbacks to this, regarding the extra lines a SATA power cable has?

 

[VirtualLarry]

I am using a molex to SATA cable adapter for my main disk which has the OS, a Crucial M500. Are there any drawbacks to this, regarding the extra lines a SATA power cable has?

I'm not aware of any 2.5" consumer SSDs that will not function on a molex-to-SATA power lead that omits the +3.3V wire. Most draw their power from +5V. I think Intel 730 has the option to draw power from +12V, if available.

Edit: You may run into issues, though, if the molex-to-SATA power adapter isn't built to correct specs. I've used some that end up being loose, and losing power to the drive while the system is on. Not good.

 

[Stuka87]

A real SATA power connection just has other voltages on it. Specifically 3.3, 5, and 12 volt lines.

Most drives will run fine off 5 or 12 volt. Not sure if there are any that are 3.3 only out there.

 

[BonzaiDuck]

I never had a problem with patching a Molex to an SATA plug.

However! I frown on using these 8" patch cables in my own builds for anything more than fans or a hot-swap bay (not the boot/system).

Whenever I have a PSU go south, I cut all the cables before I send it for recycling, and put the cables in the parts locker. If a PSU cable is too short, I'd consider taking some of those old cables out of storage, breaking open my solder gun and kit, and modding the PSU cable so that I don't depend on additional "plug" connections.

There are a lot of accessories and peripherals that come with the patch cable in the box. Take for instance my latest obsession: an IDE-to-SATA adapter device. It's powered by another "patch" cable -- Molex to floppy-plug. Red, Yellow, Black -- all plugged in to the device. But the device doesn't use the Yellow 12V -- just the Red 5V.

Maybe we should go back and review exactly what wires and voltages are actually used by drives -- whether SSD or HDD. It never occurred to me there might be a difference between SSD and HDD.

 

[VirtualLarry]

Maybe we should go back and review exactly what wires and voltages are actually used by drives -- whether SSD or HDD. It never occurred to me there might be a difference between SSD and HDD.

Yes, most SSDs other than the Intel 730 series use +5V only.

3.5" HDDs use +12V, primarily for the motor, and +5V for the interface board / electronics.

I'm not sure about 2.5" HDDs, but I suspect that they also only use +5V.

The reason being, is that those USB-to-SATA cables used with cloning software, only support a low-powered +5V device plugged into the SATA end, and I think that they work with SSDs and notebook HDDs. They definitely don't work with 3.5" HDDs though.

 

[BonzaiDuck]

Yes, most SSDs other than the Intel 730 series use +5V only.

3.5" HDDs use +12V, primarily for the motor, and +5V for the interface board / electronics.

I'm not sure about 2.5" HDDs, but I suspect that they also only use +5V.

The reason being, is that those USB-to-SATA cables used with cloning software, only support a low-powered +5V device plugged into the SATA end, and I think that they work with SSDs and notebook HDDs. They definitely don't work with 3.5" HDDs though.

Oh, that's where it does indeed get a bit murky.

Per the IDe-to-SATA adapter, I spent a month as an electrical-know-nothing to get the ideal solution to "hot-swap" that I needed. Writing. reading. Inquiring. . . . Experimenting (whoops!). I must've executed some three RMAs for "IDE-to-USB" and similar devices. I came across one such adapter-kit probably meant for laptops, and so it demonstrated the differing power requirements you mention.

Ha! Another kit I came across was "IDE-to-USB3." It was bundled with three different AC power cables: about half the weight of the box was devoted to European or other applications of no use to me here.

In the end, I only needed a $14 adapter, some junk wires and plugs from my parts locker, and my soldering kit. Praise JEE-sus for RMA processes . . . and "refund options". . .

 

[ArisVer]

However! I frown on using these 8" patch cables in my own builds for anything more than fans or a hot-swap bay (not the boot/system).

Actually I have four SATA power cables from the PSU but I decided to use them for spinners since they are not OS drives (one of them is but I will not be using it much), thinking they might have something to do with the power down options. I have to do some reading of what the extra 3.3V lines do.

Edit. Did a bit of reading at Wikipedia.
Quoting,
"3.3 V is supplied along with the traditional 5 V and 12 V supplies. However, very few drives actually use it, so they may be powered from an old 4-pin Molex connector with an adapter."
"To reduce impedance and increase current capability, each voltage is supplied by three pins in parallel, though one pin in each group is intended for precharging."
"Two ground pins, and one pin for each supplied voltage, support hot-plug precharging."
"Passive adapters are available that convert a 4-pin Molex connector to a SATA power connector, providing the 5 V and 12 V lines available on the Molex connector, but not 3.3 V. There are also 4-pin-Molex-to-SATA power adapters which include electronics to provide 3.3 V power additionally. However, most drives do not require the 3.3 V power line."

Some of the extra pins are for hot swap and some are doubled for better power delivery.
The only thing that concerns me is whether the 3.3V lines are used by the M500 for something.

 

[BonzaiDuck]

Actually I have four SATA power cables from the PSU but I decided to use them for spinners since they are not OS drives (one of them is but I will not be using it much), thinking they might have something to do with the power down options. I have to do some reading of what the extra 3.3V lines do.

Edit. Did a bit of reading at Wikipedia.
Quoting,
"3.3 V is supplied along with the traditional 5 V and 12 V supplies. However, very few drives actually use it, so they may be powered from an old 4-pin Molex connector with an adapter."
"To reduce impedance and increase current capability, each voltage is supplied by three pins in parallel, though one pin in each group is intended for precharging."
"Two ground pins, and one pin for each supplied voltage, support hot-plug precharging."
"Passive adapters are available that convert a 4-pin Molex connector to a SATA power connector, providing the 5 V and 12 V lines available on the Molex connector, but not 3.3 V. There are also 4-pin-Molex-to-SATA power adapters which include electronics to provide 3.3 V power additionally. However, most drives do not require the 3.3 V power line."

Some of the extra pins are for hot swap and some are doubled for better power delivery.
The only thing that concerns me is whether the 3.3V lines are used by the M500 for something.

Never was a time that I avoided "learning new things" in this business, but I remember many lost weekends of "configuration detours." I would hope that Crucial would provide this information you seek in their specs and knowledge-base.

On the other hand. If you're going to use a Molex-to-SATA patch cable, why not use it for the HDDs (what you call "spinners")? In my systems, I always make the SSDs and especially boot/system disks the priority.

Sounds like you're building a system with many storage devices . . . If you find out more about the 3.3V lines, I suppose we'd all like to hear it . . .

 

[ArisVer]

From further reading I've done it looks like the 3.3V lines were added for the manufacturers but not followed much apart from 1.8" drives and some 2.5 drives.


I asked at Crucial support and the short response of a member was "Looks like the 2.5" models are 5v: http://www.micron.com/~/media/documents/products/product-flyer/brief_m500_ssd.pdf".

The specification part of the flyer.



Edit. I am using 2x1GB for storage, the SSD, a 160GB for second OS and fun, and a 2.5" 500GB that already has some bad sectors in which I am thinking of hosting a few VMs.

Overall the only thing the SATA connector is better is for hot-swap and it also has better power delivery. Well, molex was trustworthy for many years...

 

[BonzaiDuck]

From further reading I've done it looks like the 3.3V lines were added for the manufacturers but not followed much apart from 1.8" drives and some 2.5 drives.


I asked at Crucial support and the short response of a member was "Looks like the 2.5" models are 5v: http://www.micron.com/~/media/documents/products/product-flyer/brief_m500_ssd.pdf".

The specification part of the flyer.



Edit. I am using 2x1GB for storage, the SSD, a 160GB for second OS and fun, and a 2.5" 500GB that already has some bad sectors in which I am thinking of hosting a few VMs.

Overall the only thing the SATA connector is better is for hot-swap and it also has better power delivery. Well, molex was trustworthy for many years...

Like I said, I never had a problem of "Molex-to-SATA" when I used such patch cables before. I'd just never tried them with SSDs -- didn't have occasion to do so.

But this is a bit like the slightly puzzled response I got when I asked StarTech tech-support about my IDE-to-SATA adapter. Power input included the yellow wire, and I couldn't be sure if it wasn't needed for something. It wasn't. So I was able to power the adapter from a 12V port switched on or off at the caddy/bay keyswitch -- with a 5V regulator soldered into the wiring.

So with the SSDs, you'll probably sort it out, and it may be likely you don't have to worry about it. You may have to "just try it."

Looking at the chart, if these are SATA SSDs it would seem there wouldn't be a problem.

 

[ArisVer]

Just to confirm that the SSD is working perfectly on the adapter cable, been there for a few hours.
The reason I put it there was because of the case setup. I have the two 1TB in the 5.25 bays, the SSD right below in the floppy bay, and the other two disks below, it's a side bay and has quick remove access. I chose those two there since they are the first ones to replace. The SATA power cables cannot be moved(!) so they have to be used with the 5.25 and side bays.

 

[BonzaiDuck]

Just to confirm that the SSD is working perfectly on the adapter cable, been there for a few hours.
The reason I put it there was because of the case setup. I have the two 1TB in the 5.25 bays, the SSD right below in the floppy bay, and the other two disks below, it's a side bay and has quick remove access. I chose those two there since they are the first ones to replace. The SATA power cables cannot be moved(!) so they have to be used with the 5.25 and side bays.

. . . And truth is, I'd never had a problem with the Molex patch cables causing drive failure or anything similar. I'd only PREFER to use them for less essential purposes. As long as the connections aren't "wobbly" or loose, I'd say "not to worry."