Power consumption -- hysteria or reality?

[Hans L]

Using

http://www.extreme.outervision.com/psucalculator.jsp

I and others have established that my eVGA e-GeForce 7600 GT KO and eVGA e-GeForce 7600 GS consumes about 90 watts. Intel says it s Core 2 Duo E6600 consumes about 65 watts, and the rest (memory, hard drive and fans) draws another few watts. Can someone explain to me why you then need a 500 W power supply? What power-hungry monster in a modern computer have I overlooked?

[Clunk]

you dont. work out what you need with the calculator and add a bit on in case you decide to add a more powerful card or extra drives etc.

[Hans L]

But, eVGA says

"Requirements Minimum of a 400 Watt power supply.
(Minimum recommended power supply with +12 Volt current rating of 18 Amp Amps.) Minimum 450 Watt for SLI mode system.
(Minimum recommended power supply with +12 Volt current rating of 24 Amp Amps.)"

Hans L

[Chunkers]

Also need to account for peak loads / spikes on start up - not sure whether this is taken care of in the calculators.
Fans and other mechanical devices can draw extra load on start up over and above their continuous rating (although I have to admit my experience is of much larger equipment I imagine it equally applies to small stuff!)

Chnks

[scrandman]

But, eVGA says

"Requirements Minimum of a 400 Watt power supply.
(Minimum recommended power supply with +12 Volt current rating of 18 Amp Amps.) Minimum 450 Watt for SLI mode system.
(Minimum recommended power supply with +12 Volt current rating of 24 Amp Amps.)"

Hans L

To a certain degree, this is manufacturer's covering their asses in the event that someone uses an el-cheapo PSU with wildly over-rated Wattage.

[Blitzen]

But, eVGA says

"Requirements Minimum of a 400 Watt power supply.
(Minimum recommended power supply with +12 Volt current rating of 18 Amp Amps.) Minimum 450 Watt for SLI mode system.
(Minimum recommended power supply with +12 Volt current rating of 24 Amp Amps.)"

Hans L

EVGA may be good with GPU cards but their knowledge on PSUs is evidently lacking.
Dont buy any PSU nowadays that has less than 32A on the 12V (combined or not).

[Hans L]

Hell of a peak, basically doubling from normal operation. Well, I'll take you advice, and I'll certainly will get a PSU with more rather than less power (I understand that efficiency has improved quite a lot recently -- based on reviews I have read -- and is now in the low 80 %.)