I have a prototype of this board made by ATrend.
The speed rating of the MDRAM can be seen on the Chips themselfs.
SJ-5-100 means that the Chips are rated for 100MHz they are available up to 166MHz.
MDRAM shares their Address and data bus so it is a Multi cycle chip that first sends address then data over the same pins.
It is faster then normal DRAM because it has multiple banks which auto refresh when other banks are accessed.

The crystal on mine is 14.318MHz and then you still have 33MHz from the PCI bus.