Q: 1333mhz ram card on mac with 1600 MHz ram cards?

This previous response says:

No. The computer will ignore the presence of the slower RAM or fail to start up.

https://discussions.apple.com/message/12425826#12425826

I concur with IIIaass and the others....

see > Mac mini (Late 2012): Memory specifications and upgrades

Call Applecare to be sure, but it should work. I just put 1333mhz in my iMac that says it only accepts 1600mhz and, well I am posting aren't i!

It seems to be hit or miss. It works on some Macs with some memory and not with others. I would not purchase slower memory since it may not work but it I had slower memory I would try it.

It works, but your iMac will be slower than it should be.