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Tests by French site Mac4Ever.com found that current model Retina MacBook Pro machines can use their Thunderbolt 2 connections to drive the Sharp PN-K321 4K display at 60Hz when running Windows 8.1 with the latest NVidia drivers, rather than the 30Hz possible with OS X. This suggests that OS X will be able to do the same when Apple updates the rMBP video/Thunderbolt 2 drivers.

While 30Hz is good enough for movies, our own Seth Weintraub found on his bargain Seiki that it gives a poor experience when scrolling webpages, and is of course completely unusable for games. 60Hz, in contrast, gives a smooth experience when using a computer. The mystery had been why the latest Retina MacBook Pros, with Thunderbolt 2 support, were limited to 30Hz when the specs should have made them capable of double this – and the video drivers appear to be the answer …

Here’s what happens when you try to run the Sharp 4K display at 60Hz in Mavericks:

The 'squashed' display attempting to run 4K at 60Hz under Mavericks

The ‘squashed’ display attempting to run 4K at 60Hz under Mavericks

The reason for it is the way that the display is streamed.

Streaming 4K video at 30Hz requires about 8Gbps of data, which is possible with the 10Gbps bandwidth provided by a single Thunderbolt channel. Streaming at 60Hz requires Thunderbolt 2, using Multi-Stream Transport (MST). Each channel transmits two 1920 x 2160 images, seemingly alternate rows of pixels, which are combined to draw the complete image. The latest NVidia drivers can do this, the ones installed in Mavericks can’t – hence the squashed display above.

The display already works at 60Hz on the new Mac Pro machines, though Apple’s Mac Pro support page says that settings adjustments are required.

Note that these displays default to 30 Hz (instead of 60 Hz) and need to be manually configured to 60 Hz using the display’s built-in controls.

For the Sharp PN-K321, you can modify this under Settings > DisplayPort STREAM.
For the ASUS PQ321Q, you can modify this under OSD menu > Setup > DisplayPort Stream.

The good news is that this should allow current rMBP machines to display 4K video properly in a future update to Mavericks.

The one remaining question is whether the above settings changes would also work on a Late 2013 rMBP? From what we’ve been able to dig out of Apple’s website, the answer appears to be no, but if any Late 2013 rMBP owners have either of these monitors to hand, please let us know.

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16 Responses to “New Retina MacBook Pros can drive 4K displays at 60Hz – when running Windows, Mac OS needs new drivers”

  1. Yes, I have one, there is a whole discussion on Apple’s forums about this…I have the Dell UP3214Q at work — we tried to get it to work under Mavericks, using a 2013 15″ rMBP that has the 750M. No dice. Only one side of the screen appeared. The other was blacked out (ie MST is not working).

    Some were hoping that 10.9.2 is bringing MST enabled video drivers for both the 750M, Iris, and Iris Pro, but no one is actually in the office until January (at least for my team) to test it…so we will have to wait to see what happens…but it’s not looking good.

    On the page for the Sharp monitor:

    http://store.apple.com/us/product/HD971LL/A/sharp-32-pn-k321-4k-ultra-hd-led-monitor

    “Note that 4K DisplayPort operation is only compatible with the new Mac Pro (Late 2013).”

    So that doesn’t look good for late 2013 rMBP owners…not good at all.

  2. Can anyone please confirm whether there’s any means at all to use a 4K monitor either at 60Hz or 30Hz with late 2012 rMBP 13-inch?

  3. Edward Moyse says:

    “While 30Hz is good enough for movies, our own Seth Weintraub found on his bargain Seiki that it gives a poor experience when scrolling webpages, and is of course completely unusable for games.”

    *Completely unusable* for games? Really? All those 30Hz games I’ve been playing on my 360 seemed okay to me! 60Hz would be nicer of course, but unusable is clearly the wrong word to use here … ;-)

  4. I was able to see a Sharp 4K display at the Pasadena Apple store yesterday, hooked up to a Mac Pro and also to a new rMBP, both running OS 10.9.1. It looks fantastic on the Mac Pro — 60 Hz, as mentioned.

    We had to use displayport-to-HDMI for the rMBP, so it came in at 30Hz (that’s the current recommendation from Apple). The lagginess does not seem like a problem for my use case (not a gamer). What was noticeable on the rMBP was font rendering. There were rainbow artifacts around the system font, and some other fonts (e.g. Times), but not all (I think Arial was OK). It looked quite bad. I assume it’s to do with subpixel font rendering and its interaction with the left/right display scheme (“two vertical panels on left and right”) used to fill the pixels on the 4K display.

    I also assume Apple is working on better drivers for the rMBP, because this looked bad.

  5. I also have a current model (Late 2013) MacBook Pro Retina 15″ (maxed out) and am interested in the 4K output.

    Question:
    Do you think once the new (CES 2014) monitors come out with Thunderbolt 2 that the issue will be resolved?
    Or is it still going to be completely dependent on Apple updating the OS X Mavericks Nvidia drivers?

    Grateful for any replies.

    • carter barto says:

      I also have the same machine and am wondering when I can get myself a 4k monitor to watch movies AND play games. Looking forward to hearing an update on this topic.

    • dcasewoods says:

      It looks like the TB2 based LG displays WILL support MST for 60Hz. On the other hand, NVIDIA drivers in the current 10.9.2 betas get the “wha wha” as far as support for 60Hz for all DP 1.2 displays. I myself have a Late 2013 MBPr maxed out and couldn’t be more disappointed. I in fact called Apple and bitched enough that they are accepting a return for a full refund based on the fact that I feel they falsely advertised the newest MBPr with TB2.