Even if the RAM you just added is the identical part number RAM it is not guaranteed to work unless you purchased the RAM as ONE, tested, matched 16 GB. Kit.
Assuming that your RAM is AMD Phenom II approved, I'd run Memtest86+ from a floppy, CD or flash drive on one DIMM at a time to be sure they are all good. If your PC boots then you can go into the BIOS and try slower RAM freqencies or timings as the mixed RAM is also NOT guaranteed to run at the advertised speed and latencies unless bought as ONE 16 GB., tested, matched RAM Kit.
no its not amd phenom appoved it says compatile with z68 &p67 &p55 platforms