S.O.S. - Asking for eGPU advice with Mac 2017

Hello,
Hoping someone could offer some advice please!
I was using Davinci 16 Beta version on my:
iMac 2017, 3.5 GHz Quad-Core Intel Core i5, 64 GB 2400 MHz DDR, Radeon Pro 575 4 GB,
but the editing/playback was extremely slow and choppy, so I purchased a Blackmagic eGPU AMD Radeon Pro 580. This seemed to actually slow things down even more. (Not sure if my settings are incorrect or not, but I went into preferences and checked the eGPU and Main Display GPU. I've tried Metal and Open CL, but no difference with either setting)

Therefore, I purchased DaVinci Resolve Studio 17, as I was under the impression that I could use both my internal gpu and the eGPU together, in hopes of increasing my workflow, but things still actually seem to work even slower.

Now, I'm looking at upgrading once again, by purchasing a Razor Core X with an AMD Radeon RX 5700 XT card in hopes of solving this issue, so I don't have to pull any more hair out of my head, trying to edit 4k footage with colour grading, etc..

Can someone please tell me if I am chasing the proper solution here, or should I just go buy a new, faster computer, with more cores and faster CPU?

I'd be very grateful for any help! I'm getting desperate. I can no longer take days and days to edit things that should take me a couple hours to complete, and my deadline is fast approaching.

Kindest regards,
GrockCanada

I had a similar machine, albeit with the Radeon 580, and an eGPU with the same card.
It ran reasonably well, even for UHD.
But in your case the internal GPU is limiting the VRAM (DR can't pool VRAM) and 4 GB is not enough for UHD or 4K. You can try and use the eGPU only. OTOH, TB3 is not fast enough to give you the full power of an external GPU.
If you don't want to shell out the money, try to work in HD and only switch to UHD for delivery. If that doesn't work, it's time for a new machine.

Hi Uli,

Thanks again, for your reply! You shared som advice last year with regards to the same product.
I tried using only the eGPU, but it still isn’t fast enough. It actually seems to be faster, using only the internal GPU.

Apple is telling me, I need to upgrade to at least an i7 8core to see any benefit from the eGPU.
Just curious, if the T3 cable isn’t fast enough to get the full benefit of the eGPU, how else would I connect it, for maximum benefit, via HDMI?

Thank you for your help!

Grock

Apple is just trying to sell you a new machine (but the wrong one).
It's true that to reap the full benefits of an eGPU you'll need a well-balanced machine, including CPU power and data throughput. Where this balance lies is highly dependent on the software, and DR is using the GPU more than anything else. I could see an 80% benefit of the eGPU for some calculations, like NR, but not for everything, by far not. So, let's get back to the drawing board:
– Do you experience "out of graphics memory" errors?
– Or general performance issue, like timeline not playing smoothly?
– Some filters not getting rendered?
Finally, what are your sources and delivery format?

BTW, you can't use an eGPU via HDMI. There is only Thunderbolt.