Can I put a switch between two external displays on a 5K iMac?

September 1, 2015 10:06 AM

I'm getting ready to replace my 2009 Mac Pro, and I have just about decided to get a retina 5K iMac. The only place where it doesn't measure up to how I currently use my Pro (and would continue doing with a new Mac Pro) is in external display support. Right now I have two monitors on my desktop for work, and an old TV on the opposite side of my office for streaming stuff to. The current Pro runs all this just fine, but it appears the iMac is limited to one external display.

Since I almost never have anything happening on the second monitor and on the TV at the same time, what I wonder is if I could run both of them into a switch, and then run that into the iMac. Would the computer recognize the frequently switching second display? Would it freak out about what was on the main display when the second one switched? And assuming the switching would be OK, would it work with a 4K second display and a 1080p TV?

posted by aaronetc to Computers & Internet (5 answers total)

Best answer: Not sure where you're seeing that you can't drive two external displays with the iMac -- although I didn't find an Apple source in a quick search,this article from Ars says:

...even though it can’t drive a second external 5K monitor, it has no problem supporting a pair of 27-inch Thunderbolt displays at 2560x1440 each.

I believe the iMac has two Thunderbolt ports. You might want to verify with Apple that both ports can be used simultaneously with Thunderbolt-(other display connector) adapters, but I think you might be in the clear here.
posted by aaronbeekay at 10:29 AM on September 1, 2015

Aha, here's a better source from Apple:

Thunderbolt ports and displays: Frequently asked questions

Systems with more than one Thunderbolt port, like an iMac, can have more than one Mini DisplayPort monitor or monitor connected with a Mini DisplayPort adapter connected as each Thunderbolt port can support one Mini DisplayPort display.

The Retina iMac has two Thunderbolt 2 ports, so I think you should be good to go, unless both of the displays you want to connect are 4K+ resolution.
posted by aaronbeekay at 10:35 AM on September 1, 2015

As a side note, if you can hold out a little longer, you might want to wait until the iMac 5k is updated with the new Skylake processors.
The integrated graphics should support 3 4k monitors
And it should support Thunderbolt 3 which will give you additional external monitor options.
My 2007 MacPro is being retired the day this comes out :)
posted by shakobe at 10:51 AM on September 1, 2015

Response by poster: @aaronbeekay: Thanks -- literally everything I found googling things like "retina imac multiple displays" would come back with language like, "the iMac can also drive an external 4K display, etc." with the seeming implication that that was the limit.

@shakobe: I would love to hold out (if for no other reason than that the Mac Pro line should also be refreshed soon), but I have a project that I need to move the current Pro to.
posted by aaronetc at 11:05 AM on September 1, 2015

I have a 5K iMac, and it has two Thunderbolt ports (I just looked).
posted by culfinglin at 9:50 AM on September 3, 2015