Nhan Nguyen, Is this happening upon trying to install the OS, or just normal operations? Secondly, is there an HBA card installed in slot #5 in the server? If so try removing it and see if the error clears itself. If so then try reseating the card and see if it repeats. If it does return see if the card functions in slot #4.   Let me know what you see.
Anyone knows which device this is? Server is crashing and rebooting. has all the latest firmware and drivers. 
PowerEdge R900 A bus fatal error was detected on a component at bus 0 device 1 
function 0