Clearing CMOS resets the system BIOS to default settings so it should be able to better detect changes in memory modules being used.
Again, the memory might be incompatible with the motherboard.
Here are lists of KNOWN compatible memory for the P8Z77-V Deluxe -
Corsair
G.Skill
If the memory being tried is NOT on any of the above lists, then it is possible the memory is incompatible. But this is not necessarily always the case, as some memory may not have yet been tested, so the memory being tested might be compatible anyway.
Note that trying to run two or more individual modules NOT from a dual channel kit may not work as the memory characteristics may be too dissimilar between the modules to allow compatible operation. This applies to modules with the same part number as well, as each module has its own unique characteristics. So it might require trying several modules (with the same part number) to find a compatible memory combination, AND assuming that the modules are compatible with the motherboard to begin with.