MacBook Pro 15" Mid 2014 with Samsung 3440 x 1440 @ 100 Hz

[bartswens]

Hi all,
I'm new to this forum so my apologies if this is not the right place to post this question.

I bought a Samsung C34F791WQU 34 inch 3440 x 1440 display. The display supports a 100 Hz refresh rate.
Somehow I can't seem to get this refresh rate. I have a mid 2014 15" MacBook Pro Retina with NVIDIA GeForce GT 750M.
I tried a HDMI cable but learned that HDMI only supports this resolution up to 60 Hz. Then i ordered a displayport 1.2 to mini displayport cable. This cable is supposed to support 4k resolution at 60 Hz, so i figured it should probably support 3440 x 1440 @ 100 Hz too.

However in my display settings menu, i can still only choose between 50 and 60 Hz refresh rate.
Before i send back the cable and order a 1.4 displayport cable, i would like to know whether the bottleneck actually is the cable, or is it just my computer that doesn't support this resolution at 100 Hz? I hope someone can help me out!

Big thanks!

Bart

 

[Amethyst1]

3840 × 2160 at 60 Hz, which your MBP supports, implies a pixel clock of 533.25 MHz.

3440 × 1440 at 100 Hz implies a pixel clock of 543.5 MHz which is higher than your MBP supports (IIRC the limit is 540 MHz).

However, 3440 × 1440 at 98 Hz implies a pixel clock of 532 MHz which should work fine.

You will need to add a custom resolution of 3440×1440@98Hz for your display (e.g. using SwitchResX) and see if it works.

 

[bartswens]

Thank you so much! I've got it running at 99 Hz now. Works awesome! Only wondering if i can now delete SwitchResX (since the 99 Hz config is now downloaded to my system i think?).

 

[Amethyst1]

Great to hear that! Uninstalling SwitchResX via its menu will also remove the custom resolution unfortunately. You'd need to back up the EDID override file SwitchResX created, uninstall it and restore the file afterwards.

 

[bartswens]

I've exported the EDID in the SwitchResX preferences menu.
I now have a .txt file starting with 'EDID report generated by SwitchResX Version 4.9.2 for display CF791'.
The next step is not completely clear to me yet. How do i restore this file after i've deleted SwitchResX?