if memory serves, can someone verify, but pc-chips used a proprietary coast module, using the pentium style, will fry the board
Correct. The manual says "128K/256K/512K/1024KB asynchronous SRAM module supported; Future will support pipeline burst SRAM module." But I've never seen one with anything larger than the 256K module, and of course the "future" pipeline burst module never came. I don't think it's even possible to use a pipeline burst L2 cache with a 486-based system(?).