# Thread: really dumb psu question :s

1. ## really dumb psu question :s

If i have a 450watt psu, for example...

Does the rating mean i hav 450W @ 12V DC output
OR
Does is mean the psu is consuming 450W of 240v ac mains?

(or, as i dont know how to convert the maths, does it potentially mean both?)

Thanx

2. ## Re: really dumb psu question :s

Originally Posted by hsncool
If i have a 450watt psu, for example...

Does the rating mean i hav 450W @ 12V DC output
OR
Does is mean the psu is consuming 450W of 240v ac mains?

(or, as i dont know how to convert the maths, does it potentially mean both?)

Thanx
It is a combination of the 3.3V,5V and 12V lines DC output.

The effiency rating is an indication of what power consumption at the wall.

What PSU do you have??

3. ## Re: really dumb psu question :s

Originally Posted by hsncool
If i have a 450watt psu, for example...

Does the rating mean i hav 450W @ 12V DC output
OR
Does is mean the psu is consuming 450W of 240v ac mains?

(or, as i dont know how to convert the maths, does it potentially mean both?)

Thanx
It's the total combined maximum DC output (but not just at 12V, as Cat explained). It'll pull more from the mains to provide that output, depending on efficiency at a given load.

4. ## Re: really dumb psu question :s

Its not really for computer use...
I want to power a 12v dc amp. I am yet to purchase an amp or psu for this yet, but in the past ive used amps around 200-300W rms with a 600W psu...

I want to buy an amp in the region of 500-800w, and i wanted to know what kind of psu ill be needing....
The psu will be connect to nothing else... Just looping central green and black wires in the 20pin to keep it on...

5. ## Re: really dumb psu question :s

Look at the table on the side of the PSU/from the manufacturers website. It'll show the outputs on the 12V lines and maximum wattage. Something like the Antec high current gamer power series will be able to give almost if not all the PSU rated wattage on the 12V rail, other PSUs won't provide all of it, but it'll be listed on the table.

eg:

http://www.antec.com/pdf/manuals/HCG...0manual_EN.pdf

Antex 620W hi current supply. Table lists 48A on 12V line, so you'll get 576W @12V DC.

6. ## Re: really dumb psu question :s

Originally Posted by hsncool
Its not really for computer use...
I want to power a 12v dc amp. I am yet to purchase an amp or psu for this yet, but in the past ive used amps around 200-300W rms with a 600W psu...

I want to buy an amp in the region of 500-800w, and i wanted to know what kind of psu ill be needing....
The psu will be connect to nothing else... Just looping central green and black wires in the 20pin to keep it on...
Hifi amp??

7. ## Re: really dumb psu question :s

Ok thanx, ill look into it wen im not just on my fone at work!

Originally Posted by CAT-THE-FIFTH
Hifi amp??
its actually a car amp for aftermarket speakers/subs....
I need a high power amp, for use indoors, but the price difference between car and ac mains amps is massive! Especially considering how cheap second hand ones can be picked up for...

8. ## Re: really dumb psu question :s

Don't know how much you are paying for your car amp and computer PSU combo but if you look at Pro amps like the Behringer in my link below you can get an 850W amp for less than £200.

Sounds like a neater solution no?

9. ## Re: really dumb psu question :s

Or you could use two of these (£150 each) in bridged mono mode and they will provide 500W per channel

http://www.alesis.com/ra500

10. ## Re: really dumb psu question :s

PSUs are most efficient at around 50% load so best if you get a wall socket watt meter and find out how much your pc uses as idle then double it and It has to be more than plenty for your PC at full and even overclocked and then you will have a very efficient PC, and if the PSU itself is 80PLUS GOLD then your PC is gonna be ECO almost...

11. ## Re: really dumb psu question :s

If you have a 450w psu depending on the efficiency rating it could draw up to 520w from the mains so beware of the wattage the psu outputs and the wattage it takes it in to produce the output wattage