BMD Shopping Guide / iMac (Mid 2017)

Hi all.

I run Davinci Resolve 14 Studio and new hardware is necessary in any case.

The BMD Shopping Guide recommends among others the (latest) Mid 2017 iMac 27" Retina 5K, quad core i7, 32GB RAM, video card: Radeon Pro 580, 8GB VRAM.

I mainly shoot 4k 150 Mbit/s (8bit, 4:2:0) and FHD 50 Mbit/s (4:2:2, 10bit). One device can deliver up to 400 Mbit/s (4k).

The BMD Shopping Guide says that "UHD timelines are practical with some performance limitations when using optical flow speed changes, temporal processing and noise reduction".

I mostly cut concert videos without speed changes etc. How nasty are the "performance limitations" then? Are there any?

Works pretty well for me, I don't even have the i7 but the i5 (with more RAM, though). The performance limitations relate to really heavy computing of effects which use more than one frame at a time.

Uli always gives good advice. Although DaVinci Resolve may require as little as 16GB memory, your system is happiest when it has RAM to spare. One of my projects uses 72GB of RAM to load and I only have 32GB in my system so it is cramped.

You don’t mention what system drive you are using. That iMac has 3x PCIe flash memory that is very high throughout. You can now use a 4TB interval flash system drive which will help it fly. I use 1TB 2x flash on my iMac late 2015 and its pretty good. Your machine should be better especially if you use all that internal SSD.


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Thank you all for your feedback. I haven't yet bought that new iMAC or any other computer. Of course, the system drive is important too. The BMD Guide mentions 1TB SSD.

The only effects in concert videos I mainly use are cross-fade andmoderate digital zooming (and a little grading), and I don't think that is really heavy computing; but I preferably will do multicam editing: 3 angles, mostly 1080p50 10bit 422 and sometimes 2160p50 10bit 422.

So, do I need an i7 with its 1TB SSD? Perhaps an i5 and a 3TB Fusion Drive could be sufficient for me too when there is Thunderbolt 3 attached storage?

I would definitely get the i7 4.2GHz, the price difference is not much and well worth it especially when it comes to realtime playback of 4K footage. As for Apple's SSD options, they are super expensive so I feel it's best to just get the 256 or 512 SDD from Apple and use external storage (Thunderbolt, USB3). With the kind of work you are describing you will be more than happy with that machine. We bought one in our studio to test drive on a project and are very impressed with it. We got the high end model (4.2 i7 with Radeon 580 Pro 8GB) with the basic 8GB of RAM, and added an extra 16GB from OWC for a total of 24GB. With an external Pegasus TB Raid, on a 60mins TV show with a mix of HD and 4K footage and tons of noise reduction and stabilization and grading, it's very snappy and and a pleasure to work with. In many cases it performs better than our 2012 12-core Mac Pro with Titan X. The Pro still works best for raw high-end 4K-5K-6K-8K footage (gotta love those cores!) and it's always gonna be faster for final export/render going to ProRes or DnxHD (again those cores). But overall the 2017 iMac is more responsive and more fun to work with. Our next step will be to try High Sierra with an external GPU.

Quick note: we get way more performance in Resolve 14 on Sierra 10.12.6 by using METAL, especially for noise reduction (an extra 10fps on some footage!) so make sure to manually select Metal. I'm really curious to see if Metal 2 on High Sierra performs even better.

I must be doing something wrong with METAL.

If I select that option, my NR drops off a cliff.

Back to CUDA and MANUAL works best for me

Any insights?

Hey Jack. Metal is only optimized for AMD. We use Metal on the iMac and CUDA on the Mac Pro.

Thanks for that tip.
I'll stop chasing performance and get back to editing..

Thank you, Francois. That's the kind of precise information I like so much. My decision has been made, it'll be the i7 4.2GHz.

I still recommend using as much of that very fast internal flash SSD as you can afford for maximum performance. 1 TB is better than a Fusion drive, but plan on having 4 TB when I upgrade from the iMac 27” late 2015 that I have.


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