I know this thread is over a month old, but I'm surprised that no one mentioned the Pcie Lane difference between the enthusiast (x & x299) and the consumer (z470) options.
For example the Core i9-10850KA supports 16 Pcie lanes, while the Core i9-10900X supports 48 Pcie lanes (at a price difference on newegg of about $100).
But when you start looking at storage options the difference adds up - for example the " ASRock X299 CREATOR LGA 2066 Intel X299 SATA 6Gb/s ATX Intel Motherboard" will (if I am reading the specs correctly) support RAID 0 on the M.2 slots (three of them). If I occupy all three slots that is 12 pcie lanes that I'm eating up right there. Add another 16 for my graphics card. Plus 4 more for my 10 gbps network adapter (this particular MB has 10 gbps built on but many don't). Totals a requirement of at least 32 Pcie lanes for full speed on all of these or double the number available on the Core i9-10850KA. (Btw, the non-threadripper AMD cpu's don't do much better; for example the Ryzen 9 3900XT has 24 pcie lanes, 4 of which are dedicated to the chipset)
I will be interested to see what the enthusiast cpu's look like in Intel's 11th gen series, as I would prefer to hold out for pcie version 4 support.