External 4k monitor says no signal from display port

Question

External 4k monitor says no signal from display port

HELP...

I have a late 2009 27" iMac running 10.10.2 Yosemite, i bought an ASUS PB287Q 4k monitor to extend my desktop. I have connected it by MDP to DP and the Mac recognises the ASUS, shows it as a display and tells me how it is connected but the display keeps saying "display port no signal"

If i run bootcamp and boot into windows 7 Ultimate on the same iMac the screen works perfectly giving me a 4k screen at 2160p to work on alongside the iMac with the same Display port cable.

If i use OS X with a MDP to HDMI connector the screen works as it should but with a max resolution of 2560 x 1440 only.

I have unplugged everything and re-connected, tried turning on the ASUS at different times, reset P Ram but still it will not work?

Obviously every part is working but just not from OS X

The ASUS is also set to display port 1.1

Please can anyone help????

iMac, OS X Yosemite (10.10.2), ASUS PB287Q

Posted on Feb 27, 2015 3:27 PM

Reply

Answer 1

Brett L

Community Specialist

Mar 1, 2015 6:47 AM in response to Wontlook back

Hi Wontlook back,

So it sounds as if you are having an issue with your MacBook Pro not working with your ASUS display only when it is running the Mac operating system, is that correct? A distressing situation to be sure. Just to be sure, I would like you to start with some very basic troubleshooting described in this article -

Apple computers: Troubleshooting issues with video on internal or external displays - Apple Support

Thanks for using Apple Support Communities.

Sincerely,

Brett L

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Answer 2

Mar 1, 2015 5:20 PM in response to Brett L

Hi Brett,

Thanks for your response, I'm on an iMac not Macbook but checked your link, All my software is up to date and there is no updates for the Asus and nothing for the mini dislayport to display port cable.

Everything works as it should via display port if i run bootcamp into windows 7 just not from OS X so would seem like a Mac Graphics driver issue perhaps??

I was hoping it would be a glitch that would correct itself by unplugging the cables or resetting the P Ram but no such luck so i am open to any other sugestions.

The iMac can see the Asus at all times just doesn't seem to send the signal to the Asus?

I would be happy to supply any logs that may shed some light on this issue.

Kind Regards

Mark

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Answer 3

Brett L

Community Specialist

Mar 2, 2015 9:41 AM in response to Wontlook back

Hi Mark,

Thank you for using Apple Support Communities. Due to the nature of the issue you described you may find more information by using another one of Apple's support resources - https://getsupport.apple.com/GetproductgroupList.action.

Brett L

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