July 21, 2015, 12:44:43 am
For Lumion the PC only requires a CPU that can process the data communications from GPU to system without slowing down the GPU. Number of cores are not important, except for multi-tasking with Lumion and other applications open.
Please refer to our forum guide: LUMION 5: Minimum hardware requirements
Most work (about 90%) is done on the GPU. During the render process the CPU is used some more for some later stages, mainly with the conversion and compression to MP4 for videos.
The i7-4790K has a Passmark
of 11238, so is above the Recommended Guidelines.
The i7-5820K has a Passmark of 12985.
Consideration for employing the more recent 2011-3 socket platform would be about investing in hardware that is more recent than the older Haswell platform, and would allow for more options in future upgrades of CPU, RAM etc.
ECC is not important or critical to Lumion.
If the friend is going to use other CAD and modelling software on the same workstation, then you may want to consider better performing CPU's and memory for that reason.
The highest clocked CPU with fastest RAM and supported by a motherboard that provides for 40+ data lanes (the newer gaming based ones) will impact on FPS when building scenes, and also best support the more powerful Titan series.