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DC Power Questions

M

mantis69666

Member
I have a power supply with these ratings:

CD Output 188W
+5V 25A max. +12V 4A max.
-5V .3A max. -12V .5A max.
+3.4V 16A max. +5Vsb 1.5A max.

From current figures I have a 10.3A consumption on +5V, 7.22A consumption on +12V, and an approx. overall of 138W total consumption.

Is the over +12V consumption a problem? What uses the +3.4V?
 
I don't know if this is highly technical, so i'll answer anyway 😉

It is not good to draw more current than the supply is rated for. Most PSU's i've used have a thermal fuse (or something like that - I dont know) that shuts off the system when you draw way too much.

where did you come up with these figured for you consumption on the 12V rail? it is possible that this doesn't normally happen - for example, to draw the 7.22A might require simultaneously spinning up all CD drives, seeking on the hard drive, and spinning up fans. that would mean that on power-on, you overstrain your power supply, but otherwise are withing the limits. still not good.

one thing to check is the voltage on the +12 rail. if it is much below 12V (11v, maybe even 11.5v) then you do need a PSU that provides more current on the 12 volt rail.
 
This figures approximate the "Peak" loads which I know are only at start up. I used the power requirements that are listed on the devices themselves or what I found in the respective manuals. Is there any program or way of determining what my true power consumption is?, short of opening up the power supply and using a multimeter.
 


<< This figures approximate the "Peak" loads which I know are only at start up. I used the power requirements that are listed on the devices themselves or what I found in the respective manuals. Is there any program or way of determining what my true power consumption is?, short of opening up the power supply and using a multimeter. >>



To find the current draw... NO. You'll have to put an ammeter on each output and measure the current.

I suspect you are okay... I'll bet 1MB of disk space that all your devices never pull "peak" current all at the same time... due to different capacitive loads on each device... when they truly turn on in relation to other devices, etc. but that is just MHO... and I have no conclusive eveidence to back it up.
 
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