Nick Militello, one of our readers emailed us to say he was having problems with Thunderbolt speeds when using an extra monitor in the chain. We investigate.

Everybody knows that Thunderbolt is meant to be quick, so quick, the cable connecting devices together isn't the weakest link or bottleneck anymore. Nick Militello has been having problems with daisy chaining his devices and monitors up, we'll let him take up the story...



Here is a detailed account of what I am finding in regards to Thunderbolt and the 2.3 17" MBP (quad core, 240gb SSD, 16GB RAM)

I have dual 27" thunderbolt displays connected to a Pegasus R6 12TB RAID 5, into a Blackmagic UltraStudio 3D.

Seeing how the Apple website states that this set up is possible, I wanted to give it a try.






Here are the results- These tests were done after a restart with no other apps running in the background. All applications are the latest and greatest along with firmware.

When the MBP is hooked up to just the R6:


When 1 thunderbolt display + R6


When 1 thunderbolt display + R6 + Blackmagic


We see a slight decrease in speed with 1 display, R6 and the Blackmagic.

However when the second display is plugged in, the speed drops considerably. Once the second monitor is added to the daisy chain, I am no longer able to get sync out of the Blackmagic box to my color correction monitor.

Here is the speed test with (2) thunderbolt displays + R6 + Blackmagic (mind you, 4 out of the 6 available devices you can plug into the line)


Here is what the monitor looks like during After Effects and Davinci Resolve playback. Both are unable to sync in 1080p (24p/59.94/29.97 etc...) FCP 7 actually works but only on 1080p 24p mode. 59.94 doesnt work on anything.


I find it very interesting that the second monitor makes all the difference.

The most confusing thing about this whole experience is that after much head scratching, I decided to plug in a 13" MBP 2.7 dual core. 8GB ram. 5400 500GB hard drive, into this exact setup. I was getting 225 mb/sec write speed instead of 165 mb/sec and After Effects could sync to the monitor. It is odd that the speed increase to just 225 mb/sec was enough to allow a proper signal to get through. It is like whatever is in the 13" can actually deal with the thunderbolt, at least a little better.

I also, like a few I have heard of around the net, am experiencing audio static or distortion on both Thunderbolt display's internal speakers any time I access the R6 in the line.

So here is my Thunderbolt finding. Please let me know if anyone has any thoughts or comments.

(other items testing)

-Switched video card to not auto switch. Just use high performance.
-Went to Apple, bought a brand new 17" 2.5, stock. Tested it, same exact results.
-Moved all the items around in the daisy chain to see if one item has to be first. No luck.
-Laptop monitor open and closed, same result.
-Reinstall OS.
-Brand new motherboard.
-New hard drive
-New RAM
No luck again.

Overall, if they can actually get this to work, I really do think that thunderbolt is the future. I feel that my 17" quad core is faster than my 8 core 2.93 Mac Pro. I feel like it handles FCP and AE way better except for this issue.


Many thanks to Nick for supllying the information and doing some serious testing. We are actually amazed that the 17" MBP will drive two 27" monitors and the Blackmagic at all!. Maybe Apple didn't test this extra load on the bus before advertising the two display and capture device idea on their website.

Written by
Top BloggerThought Leader

I am the Editor-in-Chief of FCP.co and have run the website since its inception ten years ago.

I have also worked as a broadcast and corporate editor for over 30 years, starting on one inch tape, working through many formats, right up to today's NLEs.

Under the name Idustrial Revolution, I have written and sold plugins for Final Cut Pro for 13 years.

I was made a Freeman of Lichfield through The Worshipful Company of Smiths (established 1601). Though I haven't yet tried to herd a flock of sheep through the city centre!

Current Editing

great house giveaway 2020

2020 has been busy, the beginning of the year was finishing off a new property series (cut on FCP) for Channel 4 called The Great House Giveaway. I also designed and built the majority of the graphics as Motion templates. It has been a great success and the shows grabbed more viewers in the 4pm weekday slot than any previous strand. It has been recommissioned by C4 for 60 episodes, including prime-time versions and five themed programmes. The shows have also been nominated for a 2021 BAFTA.

Tour de france 2020
Although both were postponed to later in the year, I worked again on ITV's coverage of the Tour de France and La Vuelta. 2020 was my 25th year of editing the TdF and my 20th year as lead editor. The Tour was the first broadcast show to adopt FCPX working for multiple editors on shared storage.


BBC snooker the crucible

BBC's Snooker has played a big part in my life, I've been editing tournament coverage since 1997. I'm proud to be part of a very creative team that has pioneered many new ideas and workflows that are now industry standard in sports' production. This is currently an Adobe Premiere edit.

amazon kindle BF

Covid cancelled some of the regular corporate events that I edit such as trade shows & events. I was lucky however to edit, from home, on projects for Amazon Kindle, Amazon Black Friday, Mastercard and very proud to have helped local charitable trust Kendall & Wall secure lottery funding.

As for software, my weapon of choice is Final Cut Pro and Motion, but I also have a good knowledge and broadcast credits with Adobe Premiere Pro, MOGRT design and Photoshop.

Plugin Design & Development

I'm the creative force behind Idustrial Revolution, one of the oldest Final Cut Pro plugin developers. It hosts a range of commercial and free plugins on the site. One free plugin was downloaded over a thousand times within 24 hours of release.

I also take on custom work, whether it is adapting an existing plugin for a special use or designing new plugins for clients from scratch. Having a good knowledge of editing allows me to build-in flexibility and more importantly, usability.


Now in its 10th year and 4th redesign, running FCP.co has given me knowledge on how to run a large CMS- you are currently reading my bio from the database! Although it sounds corny, I am pretty well up on social media trends & techniques, especially in the video sector. The recent Covid restrictions has enabled live FCP.co shows online. This involves managing a Zoom Webinar through Restream.io to YouTube and Facebook. 

The Future

I'm always open to new ideas and opportunities, so please get in touch at editor (at) fcp.co. I've judged film competitions, presented workflow techniques to international audiences and come up with ideas for TV shows and software programs!


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