I don't need more than 40 lanes. I'd be happy if I could just get that though.
Ryzen has 20 lanes available direct to the CPU.
Intel's consumer line of chips have 16 lanes.
They both get a few more lanes via the chipset, but in the end they share the bandwidth of a small number of lanes from the CPU to the chipset between everything on board, and all slots run off of PCIe from the chipset. Use everything at the same time, and you are quickly going to run out of bandwidth.
Now, if you go up to intel's more professional offerings you have as many as 48 lanes... In theory. Truth is - however - that Intel artificially limits the number of PCIe lanes on the CPU's with a sane amount of cores. For the 6-8 core variants that make the most sense for a home pro-sumer (i7-7800x or i7-7820x) you are limited to only 28 lanes. Better than the 16 of the consumer line, but still wholly inadequate. If you want 40+ PCIe lanes, you need to get at least a 10 core variant, and then your clock speed drops
It's crazy to me that in 2018 Intel's offerings are worse than in 2011 when I bought my hexacore i7-3930k which overclocked to 4.8Ghz on all cores and had 40 PCIe lanes.
Then there is Threadripper. The 64 lanes it offers are awesome. In the first generation the 1900x was pretty decent. 8 cores, none of that NUMA trouble with cores on different packages, and all the lanes you'd want. Then for some crazy reason this ideal CPU disappeared from the 2xxx threadripper lineup. The lowest model is the 12 core 2920x, which thus has cores across different packages so you have to deal with game modes and all that nonsense, and for some crazy reason it's clocked LOWER than the 16 core variant. Fewer cores should allow for higher clocks, right? So, the situation got worse in the second gen of threadripper, and who the hell wants to buy last generations chip with last generations clocks and IPC?
I'm hoping AMD gets their sanity back and offer an 8 core threadripper based on zen2, binned for max clocks within the 8 core power envelope, with all 64 PCIe lanes available and all cores on the same package so it doesn't require any of that game mode / NUMA nonsense.
1900x had cores across package, not sure where you get that it's any different than a 1920/2920 or 1950/2950. It had 4 cores on each die but with the full l3 cache of both ccx. The only chips that really have the numa issues are the 2970 and 2990 as they have die with no direct memory access. All the rest do. That's why I said 2950 would be your ideal as it has higher clocks than anything am4 and each die have 2 channels of ram each (so each ccx has direct ram access). A 2900x would just be each die cut to 4 cores, same as the 1900x is. You could save some money with that setup but there'd be no performance benefit - actually the opposite as the boost curve would be higher for sub 8 core loads on the 2950.