Can this be used as an extra monitor for an iMac Pro?

The 5K version of this monitor clearly specifies that the interface is Thunderbolt 3. This one only says USB-C. But non-thunderbolt monitors don't seem to work on the iMac Pro.

  • Asked by fn from Bruichladdich
LG UltraFine 4K Display

LG UltraFine 4K Display

Product No Longer Available

2 Answers from the Community

  • Yes, the LG UltraFine 4K Display can be used with the iMac Pro.

    In fact you can connect up to four of these LG 4k monitors. I use three different combinations of LG monitors with my iMac Pro:

    • Three UltraFine 4K displays.
    • Two UltraFine 5K displays.
    • One UltraFine 5K and two 4Ks.

    Works very well in any of these configurations. The cable requirements are very confusing though. The cables that come with these 4K and 5k monitors work fine, however:

    • The 4K and 5K cables are not interchangeable. Not surprising that the 4K cable does not support the 5K monitor, but it is surprising that you can't use the LG 5K cable (or ANY 5K Thunderbolt 3 cable) to connect the 4K display. (As I understand it this is because the 4K display has USB-C connectors but does not actually support Thunderbolt; it uses DisplayPort over USB-C vs the 5K which uses "dual" DisplayPort over Thunderbolt 3. Clear as mud, right?)

    • The USB-C video cable that comes with the 4k is rather short, about 1m. I've been unable to find ANY longer USB-C cable that works. I think maybe it's impossible to make a longer USB-C video (non-Thunderbolt) cable that works. This is a problem with some multi-monitor setups with the iMac Pro as your arrangement of the displays is somewhat constrained by the length of the cables.

    Measure carefully before purchasing. USB-C connectors (cables and ports) are easily damaged. If you stretch them at all tight you will inevitably damage the ports in either your computer, you LG monitor or both.

    • Answered by David L from Charlottesville
  • All the Thunderbolt 3 ports of the iMac Pro also support USB-C with DisplayPort alt mode so USB-C displays like the LG UltraFine 4K will also work. A Thunderbolt 3 port supports USB 3.1 gen 2, DisplayPort 1.2, HDMI 1.4, or Thunderbolt 3. Thunderbolt 2 and Thunderbolt 1 works with a Thunderbolt 3 to Thunderbolt 2 adapter. HDMI 2.0 works with an active DisplayPort or USB-C to HDMI 2.0 adapter. DVI and VGA also work with adapters. You can chain some adapters together: like USB-C -> DisplayPort -> HDMI

    • Answered by Joseph V from Fort Langley