1500VA UPS + Sleepy Mac Pro Wakes Up = Overload

Question

I have seen a couple of people mention that upon a "USB event" informing a sleeping Mac Pro that the UPS went on battery that the UPS then went into overload. I also have precisely this same problem for a stock Mac Pro. The discussion I am referencing is:
http://discussions.apple.com/thread.jspa?messageID=3052641
My question is, is this normal? The Mac Pro shouldn't draw in an instant over 1440VA (120V * 12A) for a stock system because there isn't any additional electronics requiring that power. If it WERE a fully loaded, fully connected (external devices included) system, then sure I can understand this. However, the computer shouldn't draw what it doesn't need. I DO understand that there can be spikes in current draw, but more than 1440VA? Is this normal?
Is there anyone who has a UPS and a Mac Pro who has put the Mac Pro to sleep, lost power to the UPS (intentionally by pulling the cord or by accidental power loss), had the Mac Pro wake up WITHOUT overloading the UPS? Even when my Mac Pro is the only device connected to the UPS it will overload the UPS upon wake-up.
To add a stipulation, if the Mac Pro is asleep but there is no communcation link (usually USB) between the Mac Pro and the UPS, then the Mac Pro will sleep happily in ingorance of power loss and thus not try to wake up and overload the UPS. However, if you try to wake up the Mac Pro while the UPS is on battery, then that may not be a good thing.
If anyone CAN put their Mac Pro to sleep while on a UPS and lose power, then what is your UPS's ratings and is your Mac Pro the stock configuration?
Thanks. Just trying to determine what is normal for the Mac Pro. Currently I am NOT putting it to sleep and all is just fine even when my CRT monitor has to wake from sleep (we've had two power outages within the last three days, besides my own intentional power loss tests).

Answer 1

120V * 12A = 1440VA
240V * 6A = 1440VA
Which is close to the 1500VA limit of the UPS;
If the Mac Pro draws more than 1440VA, then it is out
of spec even if it IS just a spike. The power supply
should be covering/dampening spikes. I was told by
AppleCare that the power supply is a 980W supply.
980W is the maximum for the whole system but not
necessarily NEEDED if there are no devices needing
that much power. Apple says 250W for the stock system
at peak performance, but it would be nice to know
what is the peak spike in power draw. If there are
spikes that draw beyond even the power supply's
capability, then shouldn't there be a recall for
those systems?
It would be nice if high powered switching supplies did not have a current spike at turn-on, but they all do.
Some people have mentioned that even their lights
flicker when the Mac Pro (and PowerMac G5) is powered
on or wakes from sleep. Is that also normal?
Normal, but not desired.
One more thing. If an Apple laptop had a peak power
draw spike like my Mac Pro, then the laptop battery
would likely overload as well and shut the system
down immediately (as in power disappears immediately
rather then a nice shutdown process). Can anyone
imagine going to wake up one's laptop only to find
that upon wake-up the laptop overloads the battery
and the system shuts down (that's only possible if
you were able to power up the laptop at all which
means you'd probably have to be connected to a wall
outlet before being able to put the laptop to sleep)?
A laptop runs directly from the DC battery. The input current surge is in the input part of a power supply where the AC is converted to DC. A laptop doesn't have that. Some parts (such as disk drives and firewire ports) use 12 volts directly from the battery, Other parts, such as the backlight and CPU, need higher or lower voltages. These use switching supplies, but since they are running from DC, don't have the large input capacitors and current surges.
The ideal way to handle UPS is to run all the equipment from DC, from a set of batteries. A power supply charges the battery when AC is available. A phone exchange runs that way. Everything is designed to run on 48VDC from a set of batteries in the basement. These are kept charged by AC, or if the AC is off for too long, diesel generators. Some computer companies made 48VDC power supplies as an option for computers they sold to phone companies.
Three-phase AC input would also allow a design without a high start-up current surge, but would severely limit sales for home use.
With high powered AC input switchers, you need a larger than normal UPS, or one that is designed to handle a large start-up current spike. Such an UPS might draw too much power to run on a household circuit.
Mac Pros are getting close to the limit for home use. A dedicated circuit should be used if possible. Apple does not want to stress this, so as not to limit sales.