I am currently using software RAID on Ubuntu 10.04. Since my mainboard only supports DDR2, I want to replace it with another one. However, I'm worry about the software RAID damaged. Will the Ubuntu just boot and reform the RAID correctly after I replace the mainboard, provided all hardware components are installed properly?
Software RAID (more or less by definition) doesn't care about the hardware. As long as you connect all the disks, the software RAID will keep working. (And you connect enough disks, depending on your RAID mode, the software RAID will keep working in degraded mode.)