[Solved] 3 GPUs work, 4 GPUs fail with "couldn't allocate runtime area"

[whoacowboy]

I have a GA-Z270X-Gaming 9 and I have successfully installed High Sierra with 2GPUs, Titan Xps. (Most) everything is working fine, but enough works for a great rendering machine.

I bought 2 more to put it over the top. When I installed all 4 GPUs I get the error "couldn't allocate runtime area" and boot stops.

I took one out so there were 3 GPUs and (most) everything works.

Here is my setup

GA-Z270X-Gaming 9
Intel Core i7 6700K 4.00 GHz, Socket LGA 1151
1300W Power supply
Samsung 850 EVO 500GB
CORSAIR DOMINATOR Platinum Series 32GB RAM

I was told it might be an issue with my cpu not having enough PCIe lanes.

Any ideas on how to get all 4 GPUs working?

Thanks for your help.

 

[whoacowboy]

I finally resolved this using OsxAptioFix2Drv-free2000.efi worked. This issues are documented in this article.

I also bought a 1600W power supply but that was to just rule it out as an issue.