Inserting RAMs PC2700-333Mhz and PC3200-400Mhz in older motherboards possible ?

I have got some newer 512 MB RAMs with the following specification:

PC2700U DDR 333Mhz CL2.5
and
400MHz DDR PC3200 DIMM 3-4-4 Kingston

Can I (for testing purposes) insert them in an older Motherboard
which only understands

PC133; PC100; PC2100; PC1600

with 200; 266 MHz FrontsideBus?

In other words are the RAMs automatically "Under"-clocked or are they damaged in such a machine ?

Peter