Q: hd7950 no low level boot screen

I just bought a Sapphire Mac Edition HD7950 from OWC. If the switch is set to setting two the machine will boot straight through to the OS with only a split second of grey. If the switch is set to setting one the machine will boot straight through to the OS with only a split second of grey. Holding down the option button on either switch setting results in no video out at all: only a black screen forcing a hard reboot. I am running OS x 10.11.6. Any ideas?

MAC Pro 2010, OS X El Capitan (10.11.4), 12 core 3.43, 128 GB

Posted on Jul 25, 2016 8:44 PM

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Q: hd7950 no low level boot screen

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by lllaass,

lllaass Jul 26, 2016 1:03 AM in response to Pheidius1
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Jul 26, 2016 1:03 AM in response to Pheidius1

- Try resetting the SMC and NVRAM/PRAM
Intel-based Macs: Resetting the System Management Controller (SMC)
https://support.apple.com/en-us/HT201295
About NVRAM and PRAM
https://support.apple.com/en-us/HT204063
- Try bootting to Recovery and repair the startup disk
OS X: About OS X Recovery - Apple Support
https://support.apple.com/en-us/HT201314

Next, contact OWC
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by Pheidius1,

Pheidius1 Jul 26, 2016 3:46 PM in response to lllaass
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Jul 26, 2016 3:46 PM in response to lllaass

I already did SMC reset and Pram as well to no avail. I can't get to any of my other boot partitions much less recovery as the option key results in no video at all. I have contacted OWC.
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by Pheidius1,

Pheidius1 Jul 28, 2016 5:53 PM in response to lllaass
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Jul 28, 2016 5:53 PM in response to lllaass

I found that a dvi older dell monitor would boot the Apple screen so it is a conflict between the newer Dell monitors and the video card.
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by lllaass,

lllaass Jul 29, 2016 1:12 AM in response to Pheidius1
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Jul 29, 2016 1:12 AM in response to Pheidius1

Did both the new and old monitors use the same output on the card?
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by Pheidius1,

Pheidius1 Jul 29, 2016 3:12 AM in response to lllaass
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Jul 29, 2016 3:12 AM in response to lllaass

No, The older Dell shows the boot screen on DVI only. It doesn't even have any display ports to tinker with further.
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by lllaass,

lllaass Jul 29, 2016 5:45 AM in response to Pheidius1
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Jul 29, 2016 5:45 AM in response to Pheidius1

Seems like it may be a problem with the port on the card and not the monitor.
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Q: hd7950 no low level boot screen

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by lllaass,

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by lllaass,

by Pheidius1,

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