Power Supply Question

[dannyp1]

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.

[save2600]

Well, that's 50watts more than what I've got in my A2000. Powers 2 floppies, a Supra accelerator, 8MB Fast, 2MB Chip, CD-ROM, 1GB HD, external DCTV and a sound sampler just fine.

In a tower environment, you should be able to add another HD, a fancy accelerator with lots of RAM and a DVD ROM easily before having to worry about power restraints. I'd be more concerned with keeping everything as cool as you can.

[Zac67]

A bare 1200 probably runs below 25W.
Accelerators vary somewhat (maybe 10-40W).
HDDs power depends on size, RPM, generation, but not much more than 20W (startup) for 1.6" thick 3.5" drives (5.25" may go up to 50W!). Modern 3.5" 5400 RPM are <10W.
Optical drives ~10W.

Most probably you won't exceed 150W, but you need to make sure the 5V rail is strong enough for mainboard, accelerator and ~25% of the drives.

[Dazxy2001]

While not a full answer to what you are looking for it may help you to work out whats required for the drives your interested in using http://extreme.outervision.com/psucalculatorlite.jsp
One power supply may not be the same as another at the same wattage more so if its a generic no name brand for OEM use etc, although the label on it should provide you with a break down of the available wattage per voltage that the supply will output.

[Tenacious]

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.