Please post more information on your issue. Answer the following questions:
1. What is the make and model of the RAM in question?
2. How do you know the mobo isn't detecting the RAM?
3. If you remove all DIMMs from the mobo; press the power button; does the mobo speaker emit a long beep or a series of beeps? If a series, annotate how many long and how many short.
4. Are you sure the RAM is functional, meaning not defective? Testing the RAM with MemTest86+
will make a compelling argument.
5. What steps have you tried thus far in your troubleshooting, if any?