3.1 Mac Pro - won't power up with Radeon 7950 card installed

Question

3.1 Mac Pro - won't power up with Radeon 7950 card installed

I purchased a Sapphire 7950 card to upgrade from the little 2600 that came with the computer. When the card is installed in slot 1 with two extra power cables connected to the motherboard the computer won't power up, I just hear the power supply click. Tried swapping the power cables, tried it in slot 2, same thing. Computer boots up fine after putting the old card back in. Vendor says the card was tested thoroughly.

Spec for the 7950 is 500w. Is it needing more power than my mac can provide?

Here's my specs:

2008 Mac Pro 3,1

12GB RAM

4 SATA hard drives

1 PCIe UAD-2 card (7w power draw)

1 PCIe RME HDSPe MADI card (7w power draw)

Thanks,
Michael

2008 8-core Mac Pro-OTHER, OS X Mavericks (10.9.5), 10GB RAM, 4 internal SATA HD, UAD-2 PCIe

Posted on Jun 4, 2015 6:16 PM

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Answer 1

lllaass

Level 10

210,513 points

Jun 5, 2015 2:03 AM in response to Michael Nowak2

What if you remove the tow other PCle cards as a test? Maybe an interaction

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Answer 2

Jun 24, 2015 1:29 AM in response to Michael Nowak2

Can anyone comment on this? In general, if a Mac only goes "click" instead of booting up, is that a power issue?

I got a different card from the vendor (Nvidia GTX 680), much lower power consumption, lots of other people are using them in 3,1 Mac Pros with no issues, mine won't boot up with this video card either. Still booting fine with the original Radeon 2600 card.

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Answer 3

lllaass

Level 10

210,513 points

Jun 24, 2015 2:30 AM in response to Michael Nowak2

Have you reset SMC and NVRAM/PRAM

Intel-based Macs: Resetting the System Management Controller (SMC)

About NVRAM and PRAM

If the cards work in other computers than yo have problem with your Mac. I would say a power supply problem.

I would make an appointment at the Genius Bar of an Apple store.

Apple Retail Store - Genius Bar

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Answer 4

The hatter

Level 9

61,031 points

Jun 24, 2015 2:55 AM in response to Michael Nowak2

Where and what aux -power cable are you using?

The "500W" is the PSU and generally means a small PC is fine. Yours is 900W PSU, the PCIe rail has 75W and each 6-pin aux cable can supply 75W each so anything that does not need 8-pin (150W aux cable) is fine.

Sapphire 7950 thread posts MacRumor

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