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The Mac Pro First Generation is an Intel Xeon-based workstation computer manufactured by Apple Inc. The first generation model includes the machines from 2006 through 2008.

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Mac pro 2009 Max power draw on SATA optical bay cables

I just picked up a early 2009 4,1 Mac Pro to replace my current 2,1 Mac Pro.

In the 2,1 I'm running a custom flashed radeon 7970 with 6+8 pin power connectors. Currently in the 2,1, the 8 pin on the card is being powered by the two molex connectors for the optical drives via a converter, and the 6 pin on the card is powered by one of the connectors on the motherboard. (the second connector on the motherboard is broken om my 2,1)

Now my new machine (the 4,1) has SATA power in the optical bay, and the power spec for SATA is quite a bit lower than for the molex connectors. Would I be OK running the 6-pin on the card from the SATA power in the optical bay, and the 8-pin from both the mini 6 pins on the motherboard combined?

If I calculated properly, I should be able to draw 54W from each SATA connector at 12v (1,5A per cable, 3 cables with 12V so total of 4,5a at 12V = about 54W). 6-pin PCIe power has a max draw of 75W, so 108W from both SATA power cables should be easily enough, but since both SATA power plugs in the optical bay are powered by a single cable that splits in to two connectors, I would like to confirm this before I fry my board.

The SATA power seems to be coming from one connector on the motherboard marked "ODD PWR", can anyone confirm that? And dose anyone know the pinout for this connector? Plugging in a converter cable up in the optical bay and running it back down to the GPU seems a bit of a unnecessary hassle if I could just adapt the 6-pin directly from the 4 pin on the motherboard of the Mac Pro.

(I don't mind having to solder my own converter cables, I'm probably going to do that anyway to get them to the exact right lengths)


After measuring the connector on the board and the SATA power connector on the other end and comparing the results with the pinout of the SATA power connector I've managed to discover the pinout of the connector, and verified it by mesuring the connector on the motherboard with a multimeter with the machine turrned on.

When looking at the machine from the side pannel side:

  • Top left = +12V DC
  • Top right = +5V DC
  • Bottom left & right = GND (same for both 5V and 12V)

Surprisingly no 3,3V present on the connector.

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1 Answer

Chosen Solution

Do you have a connector for the PCIE Aux port? That's what supposed to be used.


See if this is the same card and connectors, it sounds like it on this installation video:

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Do you mean the mini PCIe 6-pin connectors on the motherboard? Yes I do have a cable for those, but the GPU i'm using requires both a 6-pin and an 8-pin connector. The 6-pin connectors are only designed to handle 75W each, and an 8-pin connector is designed to handle up to 150W. So I'm a litle reluctand to just power the 8-pin connector on the GPU from one 6-pin connector on the motherboard. I know it's been done succesfully in the past, but if posible I would like to avoid it.


OK, I'll go look at that card and think about it. I really discard for flashed PC cards. It seems like the issues they cause are just not worth the few dollars you save over a made for Mac card. And you never know if the flash was done by someone who even knows what they are doing.


Maybe not all flashed PC cards are a good idea, but mine has been working without a single issue for the last 5 or 6 months. I generated and flashed the ROM myself using the ROM creation tool netkas posted a while ago over at It now has full bootscreens and is propperly recognised as a 7970 in OS X.

The way the card is connected in the tutorial you linked is probably fine, but like I said, the 8-pin connector is hooken up straight to the mini 6-pin on the motherboard. The mini 6-pin is only designed to handle up to 75W of power draw, whilst an 8-pin connector should be able to handle up to 150W. So if the card is being put under load, it might draw more power from the logic board than the board was designed to accommodate, and fry the board.

I know that probably isn't going to happen, but like I said before, I would like to avoid that risk if possible.


Let me ask more of an electrician in on this one @oldturkey03 an see if he thinks a possible in-line fuse could be had and economically installed to protect your board and the advisability of it.

Of course the fist thing to go in these 2008-2012 machines is the video card. I'm on 2009 2 x 2.93 Eight-Core now and have a 2008 2.8 Quad Core for my bench testing machine. In both I am running the Mac Pro Nvidia GeForce GT 120 PCIe 512MB (which I have never seen fail). That's an upgrade for the 2008 machine. I tried a ATI Radeon HD 4870 flashed card but it went belly up in three months.

Personally i have not done any flashing or over clocking CPUs or GPU since the Macintosh II ci & si days.

A 5 Mhz bump on a Motorola 68030 @ 20 MHz made a major difference. I think I still have two unused MC 68882 FPU cache cards still in original boxes that I had for stock.

What CPU configuration are you running on this? And how Much RAM? What's the goal for his card? What are you trying to do?


For CPU's i'm currently running 2x 4 core (8 core total) at 2,26Ghz, 12GB of 1066Mhz memory. I'm thinking about the dual 6-core update in the future, but it's going to be a while before I've got the funds to attempt the upgrade.

The machine is mainly used for video editing and rendering in FCPX, and some very occasional light gaming. So the card won't be under full load all of the time, but during real-time playback of effects and titles FCPX dose utilise the card for rendering I believe.


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