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Engender

macrumors member
Original poster
Oct 6, 2007
94
8
Hello all,

I have a USB 3.0 PCIE card that I realized I need to run MOLEX power to. I have an open HDD slot. Is it safe or advisable to run a SATA to MOLEX connector to provide additional power to the PCIE card?

I have a Radeon RX 580 8 GB, and I'm using both of the on-board power ports to provide supplemental power to the 580. Is that necessary? I'm using my Mac Pro just as my workstation, so I'm not running any software that demands a lot out of the GPU.

Anything else I should be considering?

Thanks for your help!
 
I have a Radeon RX 580 8 GB, and I'm using both of the on-board power ports to provide supplemental power to the 580. Is that necessary? I'm using my Mac Pro just as my workstation, so I'm not running any software that demands a lot out of the GPU.
RX580 needs both 6 pin power.
 
As mentioned, keep both ports connected to your RX580. Otherwise the Mac/PSU will do a self-protect shut-off if your GPU gets stressed (even if right now you say it wont).
As for the USB 3.0 PCIE card, are you sure the additional MOLEX power is mandatory for your intended scenario?
If so, you can safely install your mentioned SATA-to-MOLEX power cable from one of the HDD bays.
 
My MacPro3,1 has four drive bays, 6 SATA connectors (two on the motherboard for SATA ODD), and two PATA connectors (for the DVDs or ODD).

I split the power on two SATA connectors 2 or 3 times to connect 4 SSDs and a USB card. The other two SATA connectors only have one SSD or HD each.
https://forums.macrumors.com/threads/pcie-ssds-nvme-ahci.2146725/post-29613683

Before that I had a molex splitter from the DVD drive bays.
https://forums.macrumors.com/threads/usb-c-cards-for-mac-pro-5-1-4-1.2093601/post-27893524
 
As mentioned, keep both ports connected to your RX580. Otherwise the Mac/PSU will do a self-protect shut-off if your GPU gets stressed (even if right now you say it wont).
As for the USB 3.0 PCIE card, are you sure the additional MOLEX power is mandatory for your intended scenario?
If so, you can safely install your mentioned SATA-to-MOLEX power cable from one of the HDD bays.

I'm not certain, but I get a "failed to properly eject" notification on my USB 3.0 peripherals when I wake my mac up. The PCIE card is the High Point 2-Port PCI-Express RocketU 1022C. I think that connecting power to the High Point card will allow it to wake from sleep properly.

Is there a specific SATA to MOLEX connector that you guys could recommend, so that I could run the connector from one of my HDD bays? I purchased this guy, and it didn't want to stay connected to the SATA connector:
 
Your cable looks good.
Have you removed/clipped the nose on one side of the plug - otherwise you can't connect it properly.
 

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I did. But, when I connected it to the HDD SATA port with the Mac Pro on its side, then righted it and booted it, the cable fell out of connection and hit the GPU fan. So, there's nothing better? I suppose I could secure it with the tiniest bit of electrical tape . . .

Is the other part in that image, with the SATA data and power inputs, something I could purchase on Amazon.com? If my cable connects that part, then it might make the connection more secure without using electrical tape.
 
Yes, it's called sth like "SATA 22Pin 7+15 Male SATA 22P 7+15 Female extension convertor Straight adapter".
But I would rather buy a flexible SATA extension cable and then connect your power cable to it.
This way you reduce the strain/lever on the Mac Pro's SATA connector and you can bond/secure both cables together how you please.
 

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