from what ive learned from others in the very recent past is the kabylake intel Pentium dual core cpu cannot do more than 4 gpus. it is possible its been fixed since but prolly not, it doesn't seem to detect any more than that, skylake g3220 intel Pentium dual core cpu is just fine at doing 6 gpus
I have rigs with g3930 Kaby Lake and haven't had any problems with 6 GPUs
what GHZ cpu though, I believe it was a specific ghz that had issues I think it was around 3.0ghz, your sounds like its higher than 3.0ghz but like I did mention it might have been fixed lol
as far as I know it was the same cpu as the g3220 skylake which I think is 3.0ghz but the kabylake version that's also 3.0ghz had issues detecting any thing more than 4 gpus, it was a very brief period a number of months ago I seen posts pop up for a little while of some people having issues with a version of the kaby lake microarchitecture, then those same posts disappeared as fast as they popped up