Leaked Gigabyte X99 motherboard manuals appear to confirm that the Core i7-5820K will only be able to address 28 PCI-Express lanes, in contrast to the 40 lanes of its superior counterparts.
Haswell-E Core i7-5820K Will Only Have 28 PCI-Express Lanes : Read more
Haswell-E Core i7-5820K Will Only Have 28 PCI-Express Lanes : Read more