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@glimpse: Hmm, does it help to use an optical Thunderbolt cable?

Uhlhorn wrote:@glimpse: Hmm, does it help to use an optical Thunderbolt cable?

nope =) no difference.. Signal is capped with x4 on Akitio & then even to x1 if You use some sort of splitter..- cable there doesn't matter at all, maybe just allow You to have longet span between Your device & eGPU (but I haven't tested those long corning cables)

But a ground loop only exists on minimum two grounding points. The first point is the iMac, the second point is the eGPU.
When I use an optical cable the two grounding points get separated again.

Thanks for the reply glimpse, your posts have been super helpful, as well as everyone on this list. I'm learning quite a bit in a very short amount of time

then setup render node with possibility to expand up to 4GPUs - this way I would have least amount of troubles.

Can you elaborate on the render node a little bit? What sort of node can I buy/build that will hook up to the trashcan, powerbook or 5k iMac? Or are you talking about a network node, either pc or cheesgrater mac? I've just been concentrating on TB setups, what are my other options? Like most small/med studios, I'm looking for best bang for my buck, expandability, and stability.

*ok - I just found this thread viewtopic.php?f=9&t=53398 - seems to answer a few questions. Your top suggestion it seems in terms of cost/performance would be to build a custom water-cooled PC with 780's (is that still true, or would 980 be better?). I don't want to work on PC, just use as network node, so would there be any difference in motherboards/ram configs?

glimpse wrote: I've tried using Akitio + backplane (call it splitter as it takes x1 & splits into 4 x16 mechanical). Worked out fine.

Your issue might be cause by grouding & other things..- anyway, both Thunderbolt part & splitter itself sits in the path of signal & that's most likelly is the problem - these signals are very sensitive. You might end up needing a lot of tinkering to get this work as You wish =)

Amfeltec says, that the AKiTiO box does not support switched splitters. This is the problem.

What backplane do You use?

Uhlhorn wrote:

glimpse wrote: I've tried using Akitio + backplane (call it splitter as it takes x1 & splits into 4 x16 mechanical). Worked out fine.

Your issue might be cause by grouding & other things..- anyway, both Thunderbolt part & splitter itself sits in the path of signal & that's most likelly is the problem - these signals are very sensitive. You might end up needing a lot of tinkering to get this work as You wish =)

Amfeltec says, that the AKiTiO box does not support switched splitters. This is the problem.

What backplane do You use?

Strange, 'cos I've used their PCIe backplane plugged into Akitio when I needed to connect custom eGPU box to MacBookAir =) & it worked..but again, I see why Amfeltec do not advice that route (It might take quite a bit of fiddling), Here You can see the box connected (I was limited to two GPUs due to OSX version limitation, but it worked as it should).

however..I would advice to get one GPU in Akitio & build propper node - this will be cheaper, much more stable & predictable. I'm not sure, but I think OSX has GPU limmit of like 5GPUs anyway (& all of those should be the same). Haven't seen anyone running more yet..& as mentioned, certain OS version drop that number down to two.. (let's say Your OS upgrades while You work & bam - You don't see soem of Your cards anymore =)

What version of OS X do You use? I am actual using 10.11.5, and it is so buggy that I plan to downgrade to 10.11.4. Perhaps the kernel panics are a problem of 10.11.5 only.

Mac OS X El Capitan should support 6 GPUs, because the preferences pane shows 6 slots.

have to look for sure, but I think it was El Capitan (...4). In the end is not about slot, or so..- there are boot & other issues..it's not about how much You can get conected, but how much You can get working stably. Been playing a lot, but haven't made more than 5work & from what I knwo soem have issues runing even 4..- so it's slippy topic with a lot of things unknown. Jsut wanted to elt You knwo so You would not get upset when gettign all the parts & experience is far from plug'n'play =)

Thanks.

I am using 10.11.5, but I can not downgrade to 10.11.4.
The El Capitan installer from the App store installs 10.11.5. The combo updater 10.11.4 is not installing on an 10.11.5 installation.

Uhlhorn wrote:Thanks.

I am using 10.11.5, but I can not downgrade to 10.11.4.
The El Capitan installer from the App store installs 10.11.5. The combo updater 10.11.4 is not installing on an 10.11.5 installation.

I know =) ..we had a lot of problems trying to roll back, but apples politics & the way they move upgrades is not very helpful.. =)