Wondering about the the recent levelonetechs youtube reviews, specially im interested on a comment about the coffeelake mobos having the last PCIe going through the chipset, does this mean that populating the last 16x will not drop the first PCIe to 8x? i always use my sound card on the last PCIe slot, and in the past i usually look for motherboards that had a 1x on the bottom to avoid the GPU going into 8x, im about to jump into coffeelake, and thus chosing a new mobo, i would love to go with a high end mobo, but all have 16x at the bottom… so im looking into ASRock Z370 Killer SLI/ac and MSI Z370 GAMING PLUS, but if on coffeelake i wont be penalized on motherboards like AsRock Z370 Taichi i would prefer it, can anyone confirm if populating the last PCIe slot will not drop down the GPU to 8x?
As of right now, it is hard to answer that.
Neither MSi nor ASRock have the boards you listed on their website (in the case of asrock, they advertise them, but do not provide specs yet).
Looking at the block diagramms for previous chipsets (Z170), I would guess you have to use the lowest physical PCIe X1 slot. Else the lanes will be split 8,4,4
In practice, having the GPU run at anything beyond PCIe Gen3 X4 is not bottlenecking you.