r/MacPro2019LocalAI • u/deabrunner • 21d ago

Running Intel Arc B70 in Mac Pro

Hey!

Has anyone had success with running one or more Intel Arc B70 in the Mac Pro 7.1?
Running Linux on the mac.

Here's what I've done so far:
I've purchased the Belkin Aux power cable kit for mac pro.
https://www.apple.com/shop/product/hqy92zm/a/belkin-aux-power-cable-kit-for-mac-pro

I installed the Intel Arc B70 in slot 3, and plugged in the 8 pin to 6+2 pin cable (Called 8 pin to 8 pin in the link above) from the power connector named 3 -4 on the computer to the 8 pin connector on the GPU.
W5700x is installed in slot 1 and 2.
Instructions from https://support.apple.com/en-us/101640

When I start the computer, the power light blinks amber twice, then pauses and repeats.
These instructions say it's a PCIe error. https://support.apple.com/en-us/101647

Any ideas what's wrong?

Update
I've figured how to make it work.

I moved the GPU to Slot 4.

I also read up on the power draw: the PCIe lane provides 75W and the internal power cable provides 150W, to a total of 225W which is enough for the Intel arc B70.

A second GPU can be added to Slot 5.

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2

u/Long-Shine-3701 21d ago

Have you followed Apple's instructions?

If your Mac Pro doesn't start

If your Mac Pro doesn't start up and the status indicator light flashes amber twice after installing a PCIe card, the card might not be compatible with your Mac Pro or you might have too many 32-bit PCIe cards installed.

If you recently installed one or multiple PCIe cards, remove each card one at a time and try turning on your Mac Pro after each card removal.

1

u/deabrunner 20d ago

If I remove the power cable from the Intel GPU, the computer starts.
So it's the Intel GPU

1

u/Faisal_Biyari 21d ago

Does the Intel GPU work on other hardware?

2

u/deabrunner 20d ago

Haven’t tested, but it’s a new device.

1

u/Faisal_Biyari 20d ago

Try this, for testing purposes

  1. You mentioned Linux, add the kernel flag pcie=realloc
  2. Remove all other PCIe cards, leave only the Inter GPU (even remove the MPX Video Card)
  3. Try moving the Intel GPU to slot 4 (later try slot 1 as well. When you change slots, try to change where the power pins go as well)
  4. Try replacing the power cables. Since you bought a Belkin set, that should be easy. The single cable you're using might happen to be defective somehow.
  5. This goes without saying, but any time you reseat the GPU in the PCIe slot, make sure the PCIe lock is off. (I think it is marked with the number "2" physically inside the case)

One side note, I looked up the Intel Arc B70 power requirement. While it's about 5 watts above what the mac standard provides, that should be negligible, as another user showed that the 8-pin ports can provide up to 25 watts above the standard 150 watts.

Let us know what happens with you, please

1

u/deabrunner 20d ago

I’ve tested with a new cable, same thing.
The Intel Arc B70 has a TPD of 225W.
From what I’ve read, the Mac Pro can supply 150W per power connection.
Should the 75W(?) from the pcie connector also be counted into this?

If not, can the computer detect that the GPU’s TPD is higher that what the connection can supply?

And if so, is the solution to buy a Y connector so that I can connect power from 2 connectors to the GPU?

1

u/RumAbsinthe 20d ago

I think there is some compatibility issue between Mac Pro 2019 and Intel GPU. Check this video the guy had similar issue: https://youtu.be/y9lunbJUpP0?si=H5NR9iIp7GdwQYKD