> ... siaip kalbejau apie usbus...

Ju skaicius (ypac USB3) susijes su HSIO skaicium ir PCI-E liniju skaicium per chipseta:
https://www.pugetsystems.com/labs/articles/Z170-H170-H110-B170-Q150-Q170---What-is-the-Difference-635/
https://www.pugetsystems.com/labs/articles/Z270-H270-Q270-Q250-B250---What-is-the-Difference-876/
http://wimages.vr-zone.net/2016/11/Intel-Z270-H270-chipsets-837x576.jpg
14 - H110
18 - B150
22 - H170
26 - Z170
25 - B250
30 - H270
30 - Z270

Tiesa, USB2.0 nenaudoja HSIO, tai jais galima uzkimst "plikas nugareles" (zona is kaires):
http://www.ixbt.com/mainboard/asus/asus-strix-z270f-gaming/photo/big/rearpanel.jpg