I just got a IIcx and the PSU label claims it can handle 12A @ +5V, 1.0A @ -12V, and 1.5 A @ +12V. I would like to install a Supermac Spectrum/24 PDQ+ video board that claims to pull 2.5A @ 5V & a whopping 2.0A @ 12V. Since the HD also pulls maybe 0.3 to 0.5A on the 12V line, I expect that I am about 0.8 to 1.0 A over the limit on the 12V line (about 10-12 watts). But I'd bet that I am under on both the 5 V line and the -12 V line. Also, I'd bet that the Supermac video card does not always draw the full 2A@12V and the PSU can probably deliver more than the rated power.

Yet I would really hate to let out the magic smoke. It may only be a $2 garage sale IIcx, but it is a Mac and I'd like it to survive and be useful. I'm just wondering how carefully everyone analyzes the power consumption budget on computers and the margins for exceeding the power limits on one voltage line by 10 or so watts.

TIA,

G4From128k

That Cory's IIsi can handle 3 HDs and the floppy suggests that its PSU has more omph than might be expected. Either that or the IIsi's PSU will soon turn into an SSU (Smoke Supply Unit) .

Hmmm.. I wonder if the amperage capacity ratings that are on the label of the PSU (or in the tech notes) are the available capacities. Thus, I don't have to worry about power consumption by the factory-default electronics like the mobo, HD, and floppy. I notice that PSU label suggests that the total power available in the IIcx is only 90 watts, but that Apple Spec claims the IIcx consumes159 watts power. Even with PSU inefficiency factored in, there is maybe a 40-50 watt discrepancy between power in and power available from the PSU.

G4From128k

Also, depending on the power supply, overloading them does not necessarily kill them. Sometimes they put out as many amps as they can, but the devices attached don't get enough juice so they do not work properly. Try stuff at your own risk!

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