Intel Coffee Lake and Kaby Lake have different LGA1151 pin layout

Intel's decision to break intercompatibility with Coffee Lake-S and older platforms caused a lot of controversy. Coffee Lake-S sticks with LGA1151 but Intel made various changes to the power delivery to better accommodate the new parts that have up to six cores.

It would probably have been easier had Intel just renamed the socket, but now we can confirm that there are indeed changes in the pin layout. The chip giant released new diagrams and they show the VSS (ground) pins increased in number from 377 to 391, the VCC (power) pins are up from 128 to 146 and the number of RSVD (aka spare pins) reduced from 46 to 25.

So this is why you can't plug a Coffee Lake-S CPU into a Z270 motherboard. For clearity, Intel should probably have named the new socket something like LGA1151v2 as that more accurately decribes the new situation.

Intel's #CoffeeLake pin changes:

Kaby Lake -> Coffee Lake

VSS (Ground): 377 -> 391 (+14)
VCC (Power): 128 -> 146 (+18)
RSVD: 46 ->25 pic.twitter.com/wu8sWLZHWZ

— David Schor (@david_schor) October 2, 2017