Making it work: Four displays on a monster iMac

Summary:David finally got his four-display, monster iMac to work reliably. This is the story of how he did it (and what not to do). Plus there are pictures.

Image: David Gewirtz

Back in November, I introduced you to my maxed-out iMac project. I wanted to build a system that could provide me all the performance i needed for both Mac and Windows applications, and mix them dynamically. Key to the project was my desire to run four (count 'em: four) displays on my iMac. I chose super-fast Flash storage, 32 gig of RAM, and the fastest processor Apple sells for the iMac.

My plan was to replace my beefy PC running two 24-inch 1920 x 1080 pixel monitors with four monitors. I wanted two monitors to be 27-inch monitors sporting 2560x1440 resolution, and my plan was to repurpose my original 24-inchers as left-wing and right-wing displays (there's a politics joke here, but I'll just let it go for now).

This would take me from a total screen footprint of 492 square inches to 1,115 square inches (thanks to the neat little screen comparison tool at It would also take me from a pixel real estate of 4.1 million pixels to 11.5 million pixels. It was going to be a big improvement and I really needed all that space for work.

So that was November. This is almost March. Things didn't go quite as smoothly as I would have liked.

First, it took me forever to get Parallels (the Windows virtualization software) to work properly on four monitors. Oh, did I mention that one of my monitors is rotated 90-degrees? No? Oh, well the software and system had to work with that, too. Parallels didn't like it. Not at all.

I did solve that problem eventually (and I'm planning a write-up on the steps I took and the solution shortly), but it was not all that smooth sailing for a while.

Then there was the problem of simply not having enough ports (which turns out to be ironic -- I'll tell you why in a minute). Anyway, I wanted to be able to plug in a second 27-inch monitor (which would take one of the Thunderbolt ports, using it as a Mini DisplayPort adapter, along with a USB slot). Don't go pulling the trigger on ordering this just yet. It didn't work very well.

Next, I also wanted to connect my existing 24-inch monitor (which had an HDMI port). That took the second Thunderbolt port, again using it as a Mini DisplayPort adapter. In this case, I used a Mini DisplayPort to DVI adapter connected the DVI cable into the monitor.

That gave me connections to the 27-inch outboard monitor and one of the two 24-inchers. That also used up my two Mini DisplayPort/Thunderbolt ports. Neither of my two existing monitors had HDMI, so this was the only way to go. This also meant that I wouldn't be able to use my second spare 24-inch monitor.

But, dang-it, I wanted (nay, needed) that screen space. Okay, Plan-B. Best Buy. I hate shopping and I hate shopping at Best Buy, but I wasn't about to wait. So I hopped into the DaveMobile, drove at the paltry 45mph allowed here in central Florida, and brought home a $199 Vizio TV. Best Buy had a $239 24-inch monitor with HDMI, but this was both cheaper and would play Netflix. So during reboots, I could watch reruns of Top Gear and retain what little sanity people acknowledge I have.

Hands up if you noticed a slight problem with this plan. Anyone? Ferris? Bueller? Bueller?

Ah, good, you in the back. That's right. The current-model iMac doesn't have an HDMI port, and I'd already used up the spare DisplayPorts. Enter the DisplayLink USB-to-HDMI adapter.

Before I go on, let me point out that DisplayLink and DisplayPort are different little beasties. DisplayLink is a company that produces USB-based graphics interfaces while DisplayPort is type of display interface. I'm using both.

I added the DisplayLink adapter to drive the 24-inch Vizio TV as if it were just another monitor. It's also one of the only ways to get an extra display running on the iMac.

And there I had it all connected and even kind of working. At the far left is the 24-inc Vizio monitor, running 1920x1080. Moving to the right is the 27-inch iMac itself, rocking 2560x1440 pixels. Next is the Monoprice 27-inch ... screech ...

Okay, let's back up. As you might have noticed in the picture at the top of this article, there are two Apple logo displays: the iMac itself and an Apple 27-inch Thunderbolt display. If you've read any of my previous articles in this series, you'll recall no mention of the $999 Apple Thunderbolt display. You might even recall me crowing proudly about spending under $400 for a 27-inch Monoprice display.

Yeah, well, that didn't work.

Next up: turn the page to find out what finally did the trick...

By the way, I'm doing more updates on Twitter and Facebook than ever before. Be sure to follow me on Twitter at @DavidGewirtz and on Facebook at

Topics: Apple


In addition to hosting the ZDNet Government and ZDNet DIY-IT blogs, CBS Interactive's Distinguished Lecturer David Gewirtz is an author, U.S. policy advisor and computer scientist. He is featured in The History Channel special The President's Book of Secrets, is one of America's foremost cyber-security experts, and is a top expert on savi... Full Bio

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