I put in a new kit Vengeance 8GB 1866MHz, 9-9-9-24 memory but they wont be stable? I have increased Vdimm up to 1.55V but it failes in Prime after a few sec. Now I run them in 1600MHz, 8-8-8-24 instead but any ideas to bump up to 1866MHz?
What do I have to increase more?

Thanks in advance!