Board presses offer a number of benefits to both raw and equipped powerlifters.
Great overload can take place, as the board press allows you to handle and get a feel for heavier weights. This helps to develop triceps and lockout power, allowing you to blast through bench press plateaus.
If you are an equipped bencher, the boards are a useful tool when breaking in a bench press shirt. They help you bring the bar closer to your chest, by decreasing the number of boards as the weight increases.
If you have shoulder or pec problems, board presses can be a tool that allows you to keep pressing and working around your injury. This is only advisable in consultation with a health professional, but is certainly better than early retirement.