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Question Is drawing power from a SATA drive connector to power a PCIe card a bad idea? -- For my USB 3 card, it all works great. No power issues.

Eug

Lifer
Mar 11, 2000
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Forgive the n00b question, but I haven't done this in a long time. Is drawing power from a SATA drive connector to power a PCIe USB 3 card a bad idea?

I am updating an old Mac Pro, and the closest power source for a USB 3 PCIe card I'd like to install is one of the SATA drive bays. However, the PCIe card has a 4-in molex connector on it. So, I bought one of these adapters:




However, it won't fit. The connector is keyed differently to specifically exclude connecting to the drive bay.



There is actually a 4-pin molex connector in the case, but it's way on the other side of the case and in a completely separate compartment, so to run it by the PCIe slots would be fugly. I'm guessing this design is to limit power draw. Is this correct? Or do such cables exist to support what I want to do?

I'd just be powering USB drives and portable SSDs and such. No video cards or anything.
 

Jimminy

Junior Member
May 19, 2020
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Forgive the n00b question, but I haven't done this in a long time. Is drawing power from a SATA drive connector to power a PCIe USB 3 card a bad idea?

I am updating an old Mac Pro, and the closest power source for a USB 3 PCIe card I'd like to install is one of the SATA drive bays. However, the PCIe card has a 4-in molex connector on it. So, I bought one of these adapters:




However, it won't fit. The connector is keyed differently to specifically exclude connecting to the drive bay.



There is actually a 4-pin molex connector in the case, but it's way on the other side of the case and in a completely separate compartment, so to run it by the PCIe slots would be fugly. I'm guessing this design is to limit power draw. Is this correct? Or do such cables exist to support what I want to do?

I'd just be powering USB drives and portable SSDs and such. No video cards or anything.
That's exactly how I connected my USB3 card. It works fine. I don't know what the problem with your sata connector. Two things you might check though; Is the connector damaged or defective preventing it from plugging? Is the mac using some type of proprietary sata connectors? Or maybe it has a connector molded together with the data cable so you can't plug just the power cable?

Easiest solution is to get a molex extension cable and plug into the existing molex. Can you really see it once the case is buttoned up? I don't know much about Macs, but sounds like it has a plexiglass case? Maybe so you can see twinkling RGB stuff.
 

Eug

Lifer
Mar 11, 2000
22,826
369
126
That's exactly how I connected my USB3 card. It works fine. I don't know what the problem with your sata connector. Two things you might check though; Is the connector damaged or defective preventing it from plugging? Is the mac using some type of proprietary sata connectors? Or maybe it has a connector molded together with the data cable so you can't plug just the power cable?

Easiest solution is to get a molex extension cable and plug into the existing molex. Can you really see it once the case is buttoned up? I don't know much about Macs, but sounds like it has a plexiglass case? Maybe so you can see twinkling RGB stuff.
This is what the case looks like inside:

mac-pro-side-open.jpg

The cover is solid aluminum, so no, you can't see inside.

In the pic you can see the PCIe slots on the right. The four small rectangular things above them and to the left are the drive sleds covering the SATA drive bays. The top left compartment on the left is for the optical drives and that is where the 4-pin molex connector is.

Anyhow, you are right. The SATA port in the drive bay is built in such a way that you can plug in a SATA drive just fine, but you can't attach just a SATA power cable:

IMG_0329.jpeg

If you see the cable end vs. a drive, there is that tab on the right of the cable connector that shaped differently than on the drive.

IMG_0330.jpeg

So the drive fits the slot but the cable doesn't. However, I suppose if I just remove that tab on the cable connector, it would work.

Is this just a Mac thing, or are other drive bays often like this? Would it be safe to remove that tab?

EDIT:

Nope, this is not just a Mac thing. It's a similar design on my 2.5" to 3.5" drive adapter. A separate SATA power cable won't fit because of that differently shaped tab. So I guess they do this on purpose for whatever reason, perhaps to prevent people from drawing too much power from some SATA drive connectors built to power just one drive.

IMG_0333.jpg
 
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Jimminy

Junior Member
May 19, 2020
24
8
41
This is what the case looks like inside:

View attachment 27596

The cover is solid aluminum, so no, you can't see inside.

In the pic you can see the PCIe slots on the right. The four small rectangular things above them and to the left are the drive sleds covering the SATA drive bays. The top left compartment on the left is for the optical drives and that is where the 4-pin molex connector is.

Anyhow, you are right. The SATA port in the drive bay is built in such a way that you can plug in a SATA drive just fine, but you can't attach just a SATA power cable:

View attachment 27594

If you see the cable end vs. a drive, there is that tab on the right of the cable connector that shaped differently than on the drive.

View attachment 27595

So the drive fits the slot but the cable doesn't. However, I suppose if I just remove that tab on the cable connector, it would work.

Is this just a Mac thing, or are other drive bays often like this? Would it be safe to remove that tab?

EDIT:

Nope, this is not just a Mac thing. It's a similar design on my 2.5" to 3.5" drive adapter. A separate SATA power cable won't fit because of that differently shaped tab. So I guess they do this on purpose for whatever reason, perhaps to prevent people from drawing too much power from some SATA drive connectors built to power just one drive.

View attachment 27597
I think it's just that the two connectors (power and data) are made into one piece, not to prevent using them in certain circumstances. Not just a mac thing: All the usb to sata adaper cables I've seen are made this way too. Also, I've seen sata extension cables with these all-in-one connectors. In fact, you could use one of those and cut the other (female) end off and install a molex connector, but you'd have to make sure you got the right wires, and might need a soldering iron to put the molex pins on. Not worth the effort to me.

Those [ and ] things at the sides of the power cable connector are just "centering" guides to make the female connector line up. I guess you could try removing it, and the "L" shaped key should ensure the contacts are lined up. There's no latching function, so probably work fine.

I'm pretty sure any sata power connection has enough power for things like a few external 2.5" drives and such. Maybe not for those newer fast charging ports etc. Usb 3 only takes a max of .9 amp per port from the 5V line.

I'd still just go with a simple molex extension cable myself. But I'm lazy :)
 
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Eug

Lifer
Mar 11, 2000
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I cut off the tab. Perfect fit, and the leads remain aligned because the tab on the left and the L on the right keep it in the right location.

Tab removed:

IMG_0334.jpg

Installed:

IMG_0336.jpg

Unfortunately, there are no Mac drivers. :confused_old: The OS actually sees and reports the info about it, but says there are no drivers installed.

However, I'll keep it in the machine for when I install Windows 10. Hopefully their old Windows 7 driver will work.
 
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Jimminy

Junior Member
May 19, 2020
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Windows 10 (and 8) have the USB 3.0 drivers built in.
Specifically for this card? It's a D-Link DUB-1310. Chipset is NEC.
Win 10 automatically installs a generic microsoft driver, and for me, it works well. Macs might require something else. You might have to scrounge for that.

Glad snipping off the end bit of the connector worked out.
 
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Eug

Lifer
Mar 11, 2000
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Win 10 automatically installs a generic microsoft driver, and for me, it works well. Macs might require something else. You might have to scrounge for that.

Glad snipping off the end bit of the connector worked out.
Its for all USB 3.0 controllers, I've never seen a USB 3.0 manufacturer driver for Windows 10. Linux is the same way.
Thanks guys. As you said, Windows 10 automatically installed the Microsoft generic USB 3 driver.

I updated OS X to 10.11.6 El Capitan but the card is still not supported, but that’s OK. It’s not mission critical and if I really want it I can get a different USB 3 card that works in OS X as well.
 

Eug

Lifer
Mar 11, 2000
22,826
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Hmmm. I tried transferring a 1+ GB zip file over USB 3 in Windows with the new card, and it was actually slower than through the native USB 2 ports.

So it seems this MS driver doesn’t work so well in this particular setup. However, I know in my other Windows machine that the card worked at full USB 3 speeds in Windows 7 using their Windows 7 driver. The reason I removed the card though was because it caused system instability in that particular setup.
 

Eug

Lifer
Mar 11, 2000
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369
126

NEC spun that off some time ago.

Yes thanks. It does get recognized as a Renasas device. I'll try the D-Link Windows 7 drivers at another time.

It seems Windows 10 has a habit of overwriting drivers though. I installed the Apple Realtek BootCamp audio drivers for Windows 7 to get proper audio output and that works fine, but each time I do a major Windows 10 feature update (since my install disc is 1709), Windows deletes the Realtek drivers and substitutes its own. Unfortunately, MS's audio driver ironically causes the machine to completely lose audio output. Then I have to reinstall the Windows 7 Realtek drivers to get my sound back.

The good news is that Windows 10 detects and installs working drivers for my Mac ATI Radeon 5770 GPU, my OEM Broadcom WiFi module, my OEM Cambridge Silicon Radio Bluetooth module, and for both my Apple Bluetooth Magic Keyboard and the Apple Bluetooth Magic Mouse. The bad news though is that I lose the specialized function keys on the keyboard (like volume control and optical drive eject) and I lose scrolling support on the mouse. Unfortunately, since I upgraded to Windows 10 19xx, I don't seem to be able to properly install the BootCamp drivers.
 

Eug

Lifer
Mar 11, 2000
22,826
369
126
Thanks guys. After doing some more testing, it seems overall the Windows 10 drivers are better than the D-Link Windows 7 drivers so I will stick with the Windows 10 drivers.

Also, I found a third party Mac OS X kernel extension as well, so now I have full functionality in OS X 10.11 El Capitan too. It was actually packaged up for a Clover boot loader install for hackintoshers but I just extracted the relevant kext and manually installed that and it works great in OS X. Works great.

The power draw from the SATA connector is fine too. I can run my bus-powered USB SSD no problem, and I can charge my iPad Pro too.
 

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