The i7 5930K sees all 8 Dimms, an i7 5820K sees all 8 dimms. The Imc has passed the intel test,in fact the cpu has passed all the tests. Anyone any ideas. Thanks.
Hhmmm, sounds like two memory controllers have stopped working.
After verifying your warranty is still active (here: http://www.intel.com/content/www/us/en/support/services/000006303.html?wapkw=warranty+check), you should directly contact Intel Customer Support to initiate the RMA process (you cannot do this through the forums). Here are pages where you can lookup contact information, including local phone numbers, sorted by geography:
You can use the online forms service or email, but I actually recommend calling them directly. The above links provide local or toll-free numbers in most countries and support most local languages. You could also use the chat service (start here: http://intelsupportchat.force.com/icslivechat/ics_tech_desktop_ww_english_Chat), but understand that this service is offered in English only and is subject to the normal (9:00-5:00 M-F) office hours in the Pacific (UTC-8) time zone.
Hope this helps,