and add one Hard Disk (two for Raid), one optical drive, video card and CPU, use high end motherboard,
calculate Watts and divide by 12 to get amps on 12v rail. Add 15% or 2-4 amps for safety.
Subtract 10% from combined total for maximum amperage of PSU on 12v rails for aging
Compare your power supply combined 12v rail minus 10% to your requirements.
Combined rail should not exceed requirements.