Using Dell U3014 as 2nd monitor for iMac 5k Retina 27 2017

[MacintoshDude24]

Hi,
I have a 2017 5k Retina iMac, and I would like to run a Dell U3014 as a 2nd monitor. I'm using a USB-C-to-HDMI cable to connect the iMac (USB-C) to the Dell (HDMI). With the Dell display set to 'Extended Display' in the iMac settings, at 1080p resolution and a 24 Hz refresh rate, the Dell comes to life, but it flickers off randomly and then returns. If I set the refresh rate to 50 or 60 Hz, the Dell won't turn on at all. Instead, I get the energy-saving floating message on the Dell.
So to summarise:
Dell U3014 is set to Extended Display, 24hz and Dell U3014 Colour profile. I've tried different Colour Profiles, but with the same result.
Is there anything else I should check before retiring the Dell U3014?
Many Thanks for taking the time to read this.
MD

 

[Mr_Brightside_@]

Does the issue persist with a different USB-C device? How about a different cable?

 

[PaulD-UK]

@MacintoshDude24
I used a Dell 3014E monitor with my 2019 5K iMac for a couple of years before I moved on to AS.
Everything worked fine, but I only normally used 1600/60Hz.

At first I used the DVI input with the Apple DVI adapter from a 30" Apple Cinema Display, using an intermediate TB2 dock and an Apple TB3 to TB2 adapter. That worked fine.
But it also worked with a DP cable from a TB3 dock with DP1.2 out.

It also worked fine with an Apple TV HD box connected by HDMI.

When I got an M1 mini I found the HDMI intput had an infrequent slight colour glitch, so I ran it with DP from the TB3 dock that I had used with the iMac.

The only time it didn't work was when I plugged the DP cable into the MST output port instead of the proper DP input. 😵‍💫

Maybe try it with a DP input, which I found more reliable than the HDMI, and because 1600p is at the very top edge of the old HDMI 1.4 standard, it was always tricky to get running with HDMI cables and 2012 era Macs.

Check that the HDMI input is set to the best setting, but if all the menu settings are as they should be and it doesn't work, then it's probably dying...

 

[MacintoshDude24]

Hi PaulD,
Thank you for your detailed reply. I opted not to go through a dock to avoid complications, so going directly from the iMac to the Dell seemed the best route. I suspect you are correct that it should work with a USB-C to DP adapter, since the Dell will only accept 1080p at 24Hz. Will order a cable today and report back.
Many thanks 👍

 

[MacintoshDude24]

@MacintoshDude24
I used a Dell 3014E monitor with my 2019 5K iMac for a couple of years before I moved on to AS.
Everything worked fine, but I only normally used 1600/60Hz.

At first I used the DVI input with the Apple DVI adapter from a 30" Apple Cinema Display, using an intermediate TB2 dock and an Apple TB3 to TB2 adapter. That worked fine.
But it also worked with a DP cable from a TB3 dock with DP1.2 out.

It also worked fine with an Apple TV HD box connected by HDMI.

When I got an M1 mini I found the HDMI intput had an infrequent slight colour glitch, so I ran it with DP from the TB3 dock that I had used with the iMac.

The only time it didn't work was when I plugged the DP cable into the MST output port instead of the proper DP input. 😵‍💫

Maybe try it with a DP input, which I found more reliable than the HDMI, and because 1600p is at the very top edge of the old HDMI 1.4 standard, it was always tricky to get running with HDMI cables and 2012 era Macs.

Check that the HDMI input is set to the best setting, but if all the menu settings are as they should be and it doesn't work, then it's probably dying...

Hi Paul.

New cable arrived today and worked straight out of the box. Thank you for your help, very much appreciated 👍