Installing second 4GB stick in Acer AXC 603G, PC Won't boot

[crs121pitt]

I've recently picked up a second 4GB DDR3 1600 CL11 memory stick for my Acer Aspire AXC-603G-UW15. I installed it in the secondary memory slot, as seen to the left of the fan here:

After the install, my PC will not boot. When I remove the new memory, it boots with no problem. What am I doing wrong?

http://i.imgur.com/j9Yh7De.jpg

 

[C12Friedman]

The most likely answer is that the two ram modules don't like each other and don't want to play nice together. Did you use a memory finder tool offered by the manufacturer to find the ram or did you simply purchase a stick based on specs? If you used a memory finder tool, the manufacturer will work with you to get the ram working properly since they guarantee compatibility.
Regardless, try with only the new ram module in the slot where the old ram is (slot 1) to ensure the module works - if it works okay, try the old module in the second ram slot while keeping the new ram in slot 1. If you are unable to boot with that configuration, try resetting CMOS (while keeping the ram modules in) and try starting again.