I think the bottom of the iMac needs to be facing outside. Replace the bottom intake cover with a better grill for better air intake. The top of the iMac can have thermal pads to transfer heat to the rest of the chassis and to protect the surface. This hides the Apple logo - I guess you can indicate to the user where they should place an Apple sticker. But this way may take less space because you don't need a gap for the air intake - unless you mean for the Mac mini to get air from the inside of your chassis? I'm thinking of having the mac Mini and the rest of the chassis having separate air intake/exhaust.
Four Thunderbolt ports = Four PCIe slots plus daisy chain Thunderbolt port. Four slots spaced two slots apart fits easily in the 200 mm width of the iMac - you can add 9mm of extra space for each. Or go with 3 slots with 3 slot spacing.
Find a Thunderbolt controller board like the Sonnet Echo Express SEL. Add a 90° adapter for the PCIe slot and a 90° adapter for the Thunderbolt card slot so that the Thunderbolt card will be under the PCIe slot like in the Sonnet Echo Express III-D. Do this four times. This could allow the slots to be spaced two slots apart (I can't find low profile 90° PCIe adapters for single slot spacing - maybe flexible cable adapters would work for that). Total height would be about 9 inches. This is wider than some computer cases but not as wide as some other computer cases. You'll need 9 inches for the Mac mini and its cable connections, anyway. The side containing the Thunderbolt cards can be used for power supply, cable routing, or whatever.
So in the end, you'll have something like two Sonnet Echo Express III-D's side by side with the Mac Mini hanging in the front (air intake facing front, cables facing down). Actually, might save 30 mm of depth if the MacMini is on the bottom with the Thunderbolt cards/power supply - air intake facing down, exhaust and cables facing back going through the Thunderbolt cards. This will depend on the power supply dimensions and location.
$200 per slot is a lot for a motherboard though.
@joevt We were thinking of a project where an eGFX vendor would take on rather than a custom build from existing products. Our community provides ideas/wishlist for this mini Mac tower enclosure. Sonnet has been offering an 1U rack enclosure for a while so they would be a good candidate.
@itsage If it's built by an eGFX vendor or frankensteined by a user is nearly the same thing. Certainly an eGFX vendor could make something more efficient (custom PCB for slot(s) and Thunderbolt controllers(s)). That extra efficiency in size might make it more compact, but size is constrained by dimensions of Mac mini and a graphics card and maybe a power supply. In other words, the extra efficiency might just mean there's more empty space.
@itsage, sorry for the dumb question, but when you say turn off the Mac 'manually', do you mean that you exit the installer and then hit the power button untill the it shuts down and then disconnect the eGPU?
@drogles Yes. The idea is to not click "Restart Now" when Radeon Installer completes. That way you have full control of when you connect the eGPU. Shut down through Windows logo then disconnect the eGPU once the system is off would be the safest approach.
@itsage, thanks for quick response. I'm fairly new to eGPU's and I have been battling for a couple of weeks, although my setup is "ideal" for running an eGPU. The thing disconnects randomly (it can be from 10 sec all the way up to 15 minutes before it disconnects)
I know that this is another build, but I have been trying basically everything, so I am starting to try other approaches aswell.
Maybe you can help? Or just guide me to a more similar setup? My hardware is as follows:
- 2019 MBP13. i7, 512gb m.2, 16gb mem
- Aorus Gaming box - Nvidia 1070
- External Samsung monitor (3440x1440)
- 2 meter CableMatters TB3 cable ( https://www.amazon.co.uk/dp/B07B7CQ83V/)
- 3 meter Displayport cable (eGPU -> monitor)
Sorry for hijacking the conversation here.
@drogles Your disconnection issues may have to do with the CableMatters 2m Thunderbolt 3 cable. I'd recommend testing the setup with the original .5m cable and see if the connection works more reliable. Using an Nvidia eGPU is much easier than Radeon cards in Boot Camp. You basically waits for Windows to fully load then hot-plug the eGPU.
@itsage, I allready tried the short cable, but it failed. I was wondering if it could have anything to do with the allocation of ressources in Windows?
@drogles You can actually test in macOS to isolate whether this is a Thunderbolt connection issue. Connect a set of USB mouse and keyboard to the Gaming Box and use it to observe whether there's disconnect. System Information > Thunderbolt should show Gaming Box. The GTX 1070 eGPU functionality won't work but that should not interfere with expansion port connected devices.
@itsage, as it turns out, you were right all along. I tried the short cable in MacOS, which held my ext. HDD on for like 30 mins. When I used the long cable, it wouldn’t even recognize the HDD and i could see under system information that it would connect with the gaming box for around 30 sec and then lose connection again. Thanks for the help. This could have gone on for quite some time.
This now bringes me to the next question: which 2m cable would you recommend? Or would you not recommend any 2m cable at all?
again; I cannot start to thank you enough. I was starting to lose my mind.