Cannot run two monitors (Dell U3415W)
| Computer: | Mac Pro (Late 2013) |
| Graphics: | AMD FirePro D300 2048 MB |
| OS Version: | OS X Yosemite 10.10.1 |
| Monitors: | 2x Dell U3415W |
| Monitor 1 via HDMI | |
| Monitor 2 via Thunderbolt to DisplayPort on connection port #2 |
I am having a problem getting two of my monitors to work properly on my Mac Pro. When powering on the machine, only monitor #1 works. When going to the system information (About This Mac/Display), my system recognizes both monitors. It is able to pull the model number, serial number, resolution and such for both monitors, so I know there is good communication.
When looking at the display options and trying to do a shared/extended view, monitor #2 does not display an image. In fact, the monitor goes into sleep mode. When I choose mirror mode, I get the same result. Here is where it gets odd. If I modify the frequency of monitor #2 to 50hz (PAL), it works! However, when I switch back to extended mode, monitor #2 goes back to black. In extended mode, I've tried switching between 30hz and 50hz, and nothing works.
I have tried several other combinations to rule out monitor related issues, cable issues, etc.
- HDMI on monitor #2, DisplayPort on monitor #1 - issue follows DisplayPort
- Use the Apple Thunderbolt to Thunderbolt wire to connect to the Mini DisplayPort on both monitors simultaneously
- Tried all Thunderbolt connection ports on the back of the MacPro
- Use different HDMI and DisplayPort cables
- Rebooted computer every time after each change
Any idea how I can resolve this issue? I find it strange that I can get everything to work in mirror mode if monitor #2 is at 50hz (PAL), but that's it. In that small test case, it shows to me that the Mac Pro is able to communicate with both monitors, display a clear imagine, that both monitors function properly, including all cables and connection ports. It leads me to believe it is an OS configuration issue.
Thank you.
Mac Pro, OS X Yosemite (10.10.1)
