Thank you for your reply sir. here is the datails of my ram
Transcend DDR3-1333 DDR3 4 GB PC RAM
DDR3-1333
DIMM Memory Module
240-pin Configuration
9 CAS Latency
Unbuffered
166 MHz Memory Clock Speed
8 x 256 MB DRAM Structure.
now i use 8 gb. but i want to use 16 gb. when i insert 3rd Transcend DDR3-1333 4 GB ram into my motherboard, It just starts and stops( loops). when i remove it. everything works fine. Could you please help me how to solve this?. Thank you