I have an Intel DH55TC mobo running wit
*Transcend DDR3-1333 DDR3 4 GB PC RAM (JM1333KLN-4G)
I'm thinking of adding the below Ram to the near by slot.
*Transcend JetRam DDR3 8 GB PC RAM (JM1333KLH-8G)
Will it affect my rig because of the variation from 4GB to 8GB.??
If you mean negatively affect it's certainly possible considering the mixed configuration you're going for. I recommend getting a package that equals 12GB if that's what you're shooting for.
You can check out this page for information on supported memory configurations for that motherboard:http://www.intel.com/support/motherboards/desktop/dh55tc/sb/CS-030954.htm#tested