I'm starting to think the OP got his numbers wrong. 10660mhz seems far too fast for modern ram speeds. While a Mac can use faster ram than its stock speed, they will refuse to boot if slower ram is installed.
PC-10666 is the standard RAM for the new Mac minis.
I'm guessing that PC-8500 should work, but there may be stability issues...
Personally, I'd send it back and get RAM that was at least 1333MHz, but I take a conservative approach to RAM speeds in Macs, trying to match speeds in all cases. Following this approach has meant I've never had any RAM-related issues, even using ValueRAM and other cheap stuff.