# A Question about Current Draw

• 08-28-2006, 11:59 PM
deep6
I gave it some thought but I was confused about the logic on this one:

I've pretty much made up my mind to go with the DSATX power supply, but have a question. The DSATX is a 220 watt PSU, so would pull about 18.3 amps at 12V. Which is about right, given the 20 amp fuse it comes with. My question is this:

Will the power supply always be pulling about 18 amps from the car's electrical system, regardless of the demand for power on the various rails that the DSATX produces?

I can see how either could be the case...either the PSU will only pull enough current from the car's system to provide the appropriate amount of current to satisfy the demands of the devices attached to it. Or...it would always pull the 18 amps or so and always be supplying the maximum stated current on each of the rails, regardless of whether there are devices attached to it.

The situation that comes into play is...if I have the option to get a more efficient motherboard/processor combination, I would do so to reduce the amount of power the DSATX would pull from the car's system on a regular basis. But if the DSATX will always be pulling the maximum current, I might at well get a faster (more power-hungry) motherboard/processor and utilize more of the output of the DSATX.

So, DSATX (or any other DC-DC PSU)...always drawing max current from the car's system, or does it vary based upon how much the devices attached to it are demanding?

I've tried to find an answer to this, both here and on the net at large and failed to find an answer. This is my first post here, although I've been lurking for some time...lots of great information. Thank you to all...
• 08-29-2006, 12:03 AM
Wiredwrx
Quote:

Originally Posted by deep6
I gave it some thought but I was confused about the logic on this one:

I've pretty much made up my mind to go with the DSATX power supply, but have a question. The DSATX is a 220 watt PSU, so would pull about 18.3 amps at 12V. Which is about right, given the 20 amp fuse it comes with. My question is this:

Will the power supply always be pulling about 18 amps from the car's electrical system, regardless of the demand for power on the various rails that the DSATX produces?

I can see how either could be the case...either the PSU will only pull enough current from the car's system to provide the appropriate amount of current to satisfy the demands of the devices attached to it. Or...it would always pull the 18 amps or so and always be supplying the maximum stated current on each of the rails, regardless of whether there are devices attached to it.

The situation that comes into play is...if I have the option to get a more efficient motherboard/processor combination, I would do so to reduce the amount of power the DSATX would pull from the car's system on a regular basis. But if the DSATX will always be pulling the maximum current, I might at well get a faster (more power-hungry) motherboard/processor and utilize more of the output of the DSATX.

So, DSATX (or any other DC-DC PSU)...always drawing max current from the car's system, or does it vary based upon how much the devices attached to it are demanding?

I've tried to find an answer to this, both here and on the net at large and failed to find an answer. This is my first post here, although I've been lurking for some time...lots of great information. Thank you to all...

Only when it needs it.

Michael