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Radeon HD 7950: Mac Edition only?
- Thread starter Grogfoot
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windows login screen works fine , on different computer though after flash and reboot
no activity on mac system , just stuck on repeating startup chime
So I think I know what is happening .
Before flashing the mac efi bios to card ,
1. Switch on graphics card is set to 1 and both miniDP ports are working. no apple logo boot screen though as expected.
2. with this, my 4K monitor works at 60Hz without any issues , tried reboot multiple times.
3. This monitor is shared between two computers with StartTech DP KVM supporting 2 4K monitors at 60Hz.
After flashing the mac efi BIOS to card on switch 1 on GPU ,
1. On windows the boot works fine. This is a different PC and different monitor with 2560*1600 @ 60Hz.
2. But when the card is put in to Mac Pro , the startup chime keep beeping - no progress at all.
For troubleshooting purpose,
1. Shutdown the mac pro
2. Switch the position to 2 on GPU and mac os would come up fine running 4K monitor @ 60Hz.
Note : when I am switching position to 2 , I am also switching the miniDP port.
It looks like only one miniDP port is working.
3. after login , changed the 4K @ 30Hz.
4. Shutdown the mac pro
5. Switch to position 1 on GPU and move the miniDP cable to another port
6. mac pro booted up with apple logo and allowed the boot device to be selected as well.
Further after mac os booted up , changed the 4K@60Hz and again it wont boot up and keep repeating startup chime.
So in conclusion it looks like , please confirm or share your thoughts ,
1. With mac efi flashed on to the card , only one miniDP port would work ? Is this correct ?
2. I know the card is natively not supporting 4K but without mac efi flashed , it supports just fine ? Is mac efi preventing it from overpower consumption ?
Let me know your thoughts
The HD7950 itself can do 4K 60Hz, but the Mac EFI UGA doesn't support any DP 1.2 connection.
If you want to see the boot screen on a 4K 60Hz monitor, you can switch the monitor to DP 1.1, and the boot screen should comes up. Once you boot to desktop, you can switch it back to DP 1.2 to regain the ability to display at 4K 60Hz.
Thank you , will try that. But only one miniDP port working is normal ? I have not checked the other ports like HDMI.
At this point I should be good to upgrade the system to Mojave release right ?
That’s actually normal if your card isn’t the reference card. Usually the HDMI port will be disabled after flashing, but also possible to happen on the DP (or mDP).
As long as your HD7950 can boot, you should be good to install Mojave.
Thank you. I was able to upgrade the mac pro to Mojave and it worked like a charm. Thank you for all your help.
Just one pending task is , no audio on miniDP to DP 4K monitor , speakers built into the monitor. S3221qs Dell to be specific. Any guidence on how to fix it
Came across this thread but not sure if it would work with Mojave https://forums.macrumors.com/threads/hdmi-displayport-audio-fix.2147525/