wrugoin

11-16-05, 04:36 PM

Hey Dudes,

I've got a question regarding how wattage is calculated on PSUs. Now I know that the formula is: Watts = Voltage x Amps. However, the new PSU I purchased doesn't seem to go by that formula.

I went with the Sunbeam NUUO SUNNU550-US-BK (http://images10.newegg.com/NeweggImage/productimage/17-709-004-03.JPG)

+3.3V@28A, (92.4w)

+5V@36A, (180w)

+12V1@20A, (240w)

+12V2@18A, (216w)

-12V2@0.8A, (9.6w)

+5VSB@2.5A (12.5w) = Total of 750w

By those amperages stated, I calculated that it should put out 750w, however, I'm pretty sure that the Mfg rates it at 550w for a reason. Does it have something to do with Dual 12V rails? What's the deal?

The reason I bring the issue up is because I'm replacing an Ultra 600w powersupply (http://www.moddin.org.uk/reviews/cactushead/ultra%20600W%20silver%20PSU/ultra%20600w%20silver%20psu%20002_full.jpg). If you click the link, you'll see the way they calculate the 600w rating. They follow the formula W = V x A exactly.

+3.3V@28A, (92.4w)

+5V@28A, (140w)

+12V@29A, (348w)

-3.3V@0.6A (1.98w)

-5V@2A (10w)

-12V@.06A (7.2w) = 599.6w (close enough)

To me, it seems like i'm replacing a 600W PSU with a 750W PSU by the Amperage ratings. However, I'm wondering why SunBeam would rate their PSU lower. Any help would be appreciated.

I've got a question regarding how wattage is calculated on PSUs. Now I know that the formula is: Watts = Voltage x Amps. However, the new PSU I purchased doesn't seem to go by that formula.

I went with the Sunbeam NUUO SUNNU550-US-BK (http://images10.newegg.com/NeweggImage/productimage/17-709-004-03.JPG)

+3.3V@28A, (92.4w)

+5V@36A, (180w)

+12V1@20A, (240w)

+12V2@18A, (216w)

-12V2@0.8A, (9.6w)

+5VSB@2.5A (12.5w) = Total of 750w

By those amperages stated, I calculated that it should put out 750w, however, I'm pretty sure that the Mfg rates it at 550w for a reason. Does it have something to do with Dual 12V rails? What's the deal?

The reason I bring the issue up is because I'm replacing an Ultra 600w powersupply (http://www.moddin.org.uk/reviews/cactushead/ultra%20600W%20silver%20PSU/ultra%20600w%20silver%20psu%20002_full.jpg). If you click the link, you'll see the way they calculate the 600w rating. They follow the formula W = V x A exactly.

+3.3V@28A, (92.4w)

+5V@28A, (140w)

+12V@29A, (348w)

-3.3V@0.6A (1.98w)

-5V@2A (10w)

-12V@.06A (7.2w) = 599.6w (close enough)

To me, it seems like i'm replacing a 600W PSU with a 750W PSU by the Amperage ratings. However, I'm wondering why SunBeam would rate their PSU lower. Any help would be appreciated.