Ok this is probably human error cause Im not to smart at this stuff. I recently built a comp with 4gb of ram . my mobo is standard at 1600mhz as I have 1866mhz so I had to create a extreme memory profile and it auto reads my ram @1867. Now I bought another module 4gb gskill x series installed it and the bios says somthings incompatable with hardware so I load optimized and all good. but if I set it to extreme memory thing then no good.