300W PSU equivalent to a 200W?

[Migs79]

I was with my mobo's tech support and the guy asked for my PSU's power and I told him 300W
and he also asked me to read him this:

MAX DC OUTPUT:
+3.3V 14A
+5V 20A
+12V 12A

He then told me that my psu was the equivalent of a 200W psu? does anyone know how he got this. He mentioned the +3.3V being only 14A. I don't understand and would like to know what amperage is expected of this psu? Or how he came to this conclusion.

any help would be appreciated.

 

[dakota81]

Well, this is how I figure it...

Watts is volts times amps. If you do the math and add those terms together, you get 290 as a result.

Throughing out a theoretical example, a typical system may draw most its amps from, say, the 3.3V wire, thus that rating may be the PSU's limiting factor.

 

[Migs79]

Got you now, I should've figured to use P=VI formula, now it makes sense so I'm guessing the 3.3 wire is the one that goes to the mobo, therefore it's only getting 14A. I wonder what the current the P4S333 mobo requires. I appreciate the help and thanks.

 

[krale]

He sounds dumb. Amperage is a rating of load on a circuit. A 300 amp PSU can be expected to allow another 100 amps to be pulled before failure limit.

The difference between a 200 PSU and 300 PSU, in general terms is a tower of hard drives being a raid tower or a doorstop.

Please let Tek-Tips members know if their posts were helpful.

 

[dakota81]

Quoting krale:
"He sounds dumb"
"A 300 amp PSU"


Anyways, the ATX connector from the PSU to the mobo includes wires for all 3 of the voltages, ±3.3, ±5, & ±12. I don't know how many amps motherboards, harddrives, cdroms, etc. need for operation, so if anyone else could confirm my above guess or offer an alternative, I'd certainly like to know too.

 

[Migs79]

Hey Dakota81 the formulation above is correct and the total totalamperage the 300W PSU provides is about 46A totaling about 290 Watts of Power like you had mentioned. It's written on the PSU.

Thanks for everyone's help.