Limit system...reposting my question

All motherboards split lanes like this.
I fixed that for you. Excluding HEDT systems, there aren't enough PCIe lanes to avoid this. Even in the days of the PEX 8747 or the nForce 100 / 200 chips you were still bottlenecked by the 16x lanes of the CPU. Those boards reported having upwards of 64 lanes in the case of the Intel D5400XS but in reality, the lanes still all went through the CPU.