New monitor brings questions

- How is the display connected? For 5K you need two mini splayport connected to the mac's Thunderbolt ports.

- Open Display preferences for that monitor and dot the Scaled circle and move ou cursor over the different option and you should see the different resolutions available listed on the left hand side.

- To see the resolution go to Apple icon in uper left and click on About this Mac>System Report>Hardware>Graphics/displays and the set resolutin will be listed

- To more easily change and see the available resolutions try:

SwitchResX – The Most Versatile Tool For Controlling Screen Resolutions On Your Mac

Display Menu from Mac App Store

I use Display Menu (freeversin) since without that I can't get the full 4K resolution on my Dell 4K monitor

Display Preferences will tell you the scaled resolution, which will be lower. As lllaass suggested, use:

 menu > About this Mac > More Info > Report > Graphics and Displays to get a display like this:

This will reflect the true resolution, not scaled.

The Mac has supported using multiple displays at once in an Extended desktop since circa 1987. this picture is worth 1,000 words:

Windows can be dragged to either display, or split across them and they will continue to update "the right way". This feature is supported in Mac OS X directly, and works with all well-behaved Mac Applications unless they have deliberately defeated it (iMovie was on that list for a while).

Yes, you can.

The picture above show two displays whose Icons are sized for their relative number of pixels. This is used when your displays are different resolutions. For Extended desktop, the only requirement is that the next display must be arranged so that it shares at least part of a side, top. or bottom with the other displays. Other than that, you can place those icons wherever you wish.

The mouse moves freely across the boundary, and can drag a window with it. The two displays can be as different as 64-bit color and black-and-white. Windows split across the boundary are updated "the way they ought to be" when scrolling.

Yes, I have one 4K monitor and two 1080p monitors connected to my 2013 Mac Pro

Gerald Gifford wrote:

Grant Bennet-Alder wrote:

The Mac has supported using multiple displays at once in an Extended desktop since circa 1987. this picture is worth 1,000 words:

Being able to use multiple monitors has been one of the things which has endeared me to Mac computers. I think my first multiple monitor setup was with my Power Mac G3 in about 1997.

In that time I have always had monitors with the same resolution. My question is can I use one of my old monitors (1600x1200) WITH the new Dell UP2715k and expect my computer to play nice with both?

Jerry