60Hz workaround for external 4k display??

[akaalienwarrior]

Hello, I recently purchased a 4k display and hooked it up to my 2013 imac. As soon as the display popped up i noticed terrible 30hz refresh rate with no way (that I know of) to change this. I have been researching workarounds for this issue and stumbled across a video made for the 2016 macbook pro in which the guy added script to the terminal and was able to change refresh rate. This solution did not work for me. Does anybody know how I could get 60hz 4k on this display? Thanks...

 

[kohlson]

This was discussed over at least one thread a few years ago, around the time 4K monitors became affordable - you may want to search the forums.

That said, off the top of my head you may not have the processing power to do this. I have a 2013 MBP with GT750M, and it works well driving my Dell 27 4K. I had a 2014 MBP with integrated GPU, and it was very laggy on the same system.
As well, it may be the cable and/or port (either HDMI or mDP to DisplayPort. I would start with trying another cable/port and see if that helps, or is part of the solution.

 

[jerwin]

http://www.reduser.net/forum/showthread.php?119933-4K-monitor-with-iMac-2013

Unfortunately, your Thunderbolt ports on the iMac are not Thunderbolt 2, which means you can only use the secondary 10Gbps Thunderbolt stream for video signaling. In a nutshell, that means you can only use MST mode for DisplayPort and you will be limited to a maximum of 30Hz at 4K. Even if you have the proper cable and monitor to support higher fps.

Currently, we can only get 4K @ > 30Hz out of the new Mac Pro and current generation of Macbook Pro as they both have Thunderbolt 2 ports. The HDMI ports on both of those systems are v1.4 and still limited to 4K at 30Hz or less.

I don't imagine things have changed since those posts were written.

 

[curmudgeonette]

http://www.reduser.net/forum/showthread.php?119933-4K-monitor-with-iMac-2013

The OP's issue likely isn't really a Thunderbolt version problem. Instead, the Thunderbolt 1 chip only supported DisplayPort 1.1 as a pass through mode. DP 1.1 can't carry a 4K @ 60 Hz signal. You need DP 1.2 to do that. DP 1.2 pass through arrived with the Thunderbolt 2 chip.