It isn't so much how many cards you have as whether a few of them\
are power hogs. Most cards consume very little power, but a few,
like the Transwarp and the PC Transporter use about as much power
in one slot as is budgeted for *all* the slots put together!
As for the Vulcan power supply, it's a moderate upgrade on the
stock Apple II power supply.
The real proof of the pudding is in the tasting, as always, since
the *actual* capability of any power supply is dependent on the
condition of its components, particularly its electrolytic capacitors,
whose condition tends to degrade with time and high temperatures.