Sounds like an interesting project. You do understand the following, yes?
Important Note: This board is NOT a video card. It has no display outputs for connecting a monitor. It is a processor that offloads the computation from the computer’s CPU. Also note that for operation under Windows XP, this board requires a NVIDIA graphics display board or motherboard NVIDIA graphics. This is not a requirement for Linux operation.
Assuming that isn't an issue, seems that either mobo you asked about will work. To be able to answer better, what other components do you plan to stuff into this beast (CPU, RAM, HDDs, OS, GPU, PSU, etc.)?
Also, what type of simulations are you planning on running?
Understood, mate. Just look for something similarly capable and you should be good to go. Also make sure you have a solid plan for cooling that monster of a system. It is sure to make a very good heater for what ever room it is located in.