Ok but i read 9900k 16 PCI-lanes.. is that enough for you? that why i went for a 9700x...
Yes it has, for me it is ok... going with something x299 it will mean to look for a 10 cores processor or higher (8 cores version of x299 I don't think will have better performance than the i9-9900k)... that will be probably be an investment that I will not recover.
So, I apologize to the original poster if he thinks I'm going to off-topic, let me know and I will stop.
So, what I have right now it is an i9-9900k processor, connected directly to its PCI by 16x there is a AMD Readon RX580 with 8GB. The rest of devices are conected to the 24 PCIe lanes that the Z390 chipset offers. The problem with those lines are connected to the processor via a DMI 3.0 bus (something propietary of Intel) that basically has the bandwith of the PCIe 3.0 4x bus. To those lanes I have connected a Samsung EVO 970 SSD and maybe in the future I will add a second SSD MVNe SSD there. In the future, if I externalize all my 3.5 HDD Drives (I have 4 right now connected directly via a SATA bus to my motherboard) to a NAS, I will buy a 10GBe network card.
So, my needs, I basically use Lightroom, very minimal work in Photoshop and Final Cut X, this last one it is really the reason I upgraded to this from my 2015 Macbook Pro. I just do light video editing, basically cutting 4k h264 video from my Sonys with very light color correcting. The only thing I'm thinking to change right now... it is to return the RX580 and buy a Vega 56, specially after seeing they had a price drop here in Europe this month and also seeing how much Final Cut X makes use of the GPU to render and encode h264 video. It is maxing GPU processor and memory each time I export or render the timeline after I do a small color correcting in Final Cut X.
Would I benefit not having my SSD bottlenecked by other components while editing video? Probably... but seeing the usage I think that will be minimal.
I think this system will serve me ok for the next 3 to 4 years... that it is a margin that I think Apple will give in the hypothetical case that right now they decide to go nuclear and switch to ARM based architecture or say that from version 10.X of Mac OS they will only support Macs with their T2 or equivalent chip (by margin, time they will at least support "old" Mac hardware they were selling right now without the T2 chip... I think the only Macs that don't have it are Mac Pros and normal iMacs).