Can I mix ECC and Non-ECC DIMM Module ?

No. When adding new memory, you need to match what is already in your system. ECC (error checking and correcting) modules have an extra chip that detects if the data was correctly read or written by the memory module. If the data wasn't properly written, the extra chip will correct it in many cases (depending on the type of error). Non-ECC (also called non-parity) modules do not have this error-detecting feature.<br />
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You can determine if your system has ECC by simply counting the number of black memory chips on each module. ECC (and parity) memory modules have a chip count divisible by 3. Any chip count not divisible by 3 indicates a non-parity memory module.