RAM speed issues

[Zipppy]

I'm having a bit of an issue with setting the memory speed on my motherboard, (ASUS Sabertooth 990FX). According to the manual, my memory sticks are completely compatible, and setting it on automatic forces them to go 1333 MHz instead of the intended 1866 MHz. Setting them manually any other speed than 1333 (with the proper timing) makes the system refuse to boot, the PC shuts off just as the UEFI BIOS screen shows up.

For the record, the memory kit I'm using is Corsair's CMZ8GX3M2A1866C9 kit, which is part of their Vengeance line.

If anyone has any idea on how this can be fixed, please post.