Anoying Problem with Dell U2715H and iMac Mid 2010. Incompatibles?

ChoPraTs

macrumors newbie
Original poster
Oct 27, 2009
28
1
Madrid, Spain
Hi all,

I've recently purchased a Dell U2715H monitor that I'm trying to use with my iMac 27" Mid 2010 and I'm getting a very annoying problem: the monitor starts to lost signal intermittently with its screen going black every few seconds, exactly as this video describes:


The monitor seems to work perfectly with a PS4 connected through HDMI, but not with the Mac and its Mini DisplayPort. I've also tried different resolutions and sometimes this seems to minimize the problem, but only for some hours until the screen starts to loss signal intermittently again.

It's very annoying and I don't know if it is the fault of OS X El Capitan, of my iMac or its graphics card (ATI Radeon HD 5750) or perhaps a problem caused by the Dell monitor itself, but unfortunatly they don't offer officially support to OS X systems.

So, I'm not sure that this monitor is full compatible with all Mac and I'm thinking about returning it.

Has someone here tried to use the same monitor with the same iMac model and can post their experience?

Thanks!
 

JTToft

macrumors 68040
Apr 27, 2010
3,447
792
Aarhus, Denmark
I have a hard time seeing how the monitor might be incompatible with your machine.

Possible culprits:
- Wonky Mini DisplayPort on iMac; test with another monitor.
- Bad cable; test with another cable, perhaps an HDMI one.
- Bad input on monitor; test with the Mini DisplayPort input if you're using the full size DP.
- Other defect on monitor.

Also, check that DP 1.2 isn't enabled in the monitor settings.
 

ChoPraTs

macrumors newbie
Original poster
Oct 27, 2009
28
1
Madrid, Spain
Thanks JTToft.

Yes, DP 1.2 isn't enabled in the monitor settings. Anyway, I tried both ways, enabled and disabled with the same results.

I don't think it's a wonky Mini DisplayPort on the iMac, because it's the same port that I've used since now with another monitor (but with a mini DisplayPort to VGA adapter) without any problems.

Bad cable was the first cause I thought about. But after read some other users comments in Dell forums and Youtube videos with the exact problem as mine where they're telling that they couldn't solve it after trying a lot of different brand cables, I have not too much hope that this is the problem.

Bad input on monitor also can be... but doing tests, it seems that I can solve always the problem just putting the screen in sleep mode (control+shift+eject) and awake it again moving the mouse or pressing a key. Just doing this, the problem dissapear completely and remains stable for hours and days... but can also be forced or appear again when I restart the computer, changing resolutions on System Preferences (I've tried all of them), everytime I switch off and switch on the Dell monitor, or when I select another input (like HDMI) and then come back to DP. All this situations can get the screen remains black or flickering again randomly.
 

JTToft

macrumors 68040
Apr 27, 2010
3,447
792
Aarhus, Denmark
Then it seems we've most likely landed on my fourth suggestion. Perhaps get the monitor exchanged.

From the reports you've found (I've heard scattered reports, too), were they related to your specific iMac or were they across systems? For what it's worth, I have a U2515H with the machine in my signature, and it behaves perfectly.
 

bruinsrme

macrumors 604
Oct 26, 2008
6,596
2,348
I had a similar issue with the same monitor.
Popped over to Amazon and snagged a couple better cable mini display port cables.
Lo and behold the apple mini display port seemed to be the issue.

The apple cable was the issue as I confirmed the monitor operated mini display to hdmi and mini display port to display port connection worked fine.

The monitor worked with/without the HDP setting on/off.
 
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