can the current 15 rMBP easily power an additional 4K monitor?

cmm said:

Whether it be Iris Pro GPU or the discrete GPU. Or will I notice lag, beachballs, etc? I have the 13 rMBP right now and it lags even when I use a thunderbolt Apple Cinema Display. Trying to decide if I can get away with buying a 15 rMBP again, rather than making the switch to a Mac Pro, which isn't that portable.

To be clear, I don't play games, I sit and write code all day, read, have lots of browser windows open, etc. The 8GB rMBP I have now is always overtasked. I wish I had gotten more ram. I don't remember the 15 rMBP being that bad, but I could have amnesia.

You can see my other thread, with lots more detail here: https://forums.macrumors.com/threads/1840773/

Thanks!

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In clamshell mode and extended mode, my Sharp 4K display doesn't lag at all with a GT 750M.

cmm said:

Extended mode means you can use the rMBP screen as well?

Can the 15 rMBP support one 4k monitor and another 2560x1440 screen, eg. Thunderbolt Apple Cinema Display.

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Extended mode means you can use both screens simultaneously, each displaying a different thing. For instance, I can have Xcode running on the 4K display and Safari running on the internal display.

I don't know about your second question though, I only have one 4K external monitor and no Thunderbolt displays. But theoretically, it can. Just hook it up to the second Thunderbolt port.

Can the 15 rMBP support one 4k monitor and another 2560x1440 screen, eg. Thunderbolt Apple Cinema Display.


Depending on the rMBP you're getting, you are pushing the graphic limitations of older hardware.

If you want that laptop screen on too, then it's driving three monitors with pretty high resolutions and a lot of pixels to refresh (2880x1800, 3840x2160, and another 2560x1440). It should be fine for text and static content but nothing dynamic and constantly demanding a refresh. Close the laptop display and a dual-external setup shouldn't be too bad with the 750M.

Iris Pro's 128MB of eDRAM isn't 2GB of GDDR5 devoted solely to graphic performance. And the 750M is in no way that good, resembling something slightly faster from 2012. I would wait and see what releases this year before putting down $2000 for another machine that leaves more questions than answers.

If you want to make it easier, think about a desktop. You said yourself you just sit there all day and will be locked down by cables anyways. Heck, why not make a Hackintosh? Can get a full-fledged desktop and 13" rMBP for the price of one 15" with discrete graphics.