I have an A1200 that I am putting in a custom tower. The power supply I am planning to use is 250W. How many harddrives, CD-Rom drives, etc. will I be able to safely power? Is there a "rule of thumb" as to how much power is used by a harddrive, etc.? I don't want to under power the tower, yet I believe when the Amiga BigFoot power supplies were available they were also 250W.
You can, of course, nail it down by summing the loads of each device in the tower separately for each rail (+12VDC, +5VDC, -12VDC, etc). Specs should be available from the packaging, online, or you could measure them yourself. Compare those numbers to the rating (in Amps) of each rail as printed on the power supply. In practice, you want lots of head room, say 150%, of PS capacity beyond the calculated maximum load. This should be true for all the rails. The PS should not have to struggle to supply your devices.
