My 2010 Mac Mini started beeping after powering up when I replaced the original two 1 GB SODIMMS with two 4 GB SODIMMs.

It will work if I use only one of the new 4 GB together with one of the old 1 GB. One 4 GB by itself doesn’t work.

Why doesn’t it work with both 4 GB chips, but works with mismatched RAM?

5 GB is working fine and speeding things up considerably, but is there a way I can make my Mac use all 8 GB?

Thanks!