how much power can a molex chain handle?

kajson · May 30, 2012

Hello, I"m finishing up my new build, I'm on to the cable management now, I'm using a modular 600w silent pro gold PSU, which comes with only one double molex plug cable,

Now my question is, will it handle in a chain:

1. the powerup button and usbports on top of my CM 690 II
2. the front fan being the 140mm fan
3. dvd burner (sata)
4. http://www.raidsonic.de/en/products/details.php?we_objectID=7499

I could put a different sata power cable to the dvd player if you dont think the molex cable will be able to deliver sufficient power.
a lot of devices on the cardreader device are powered by their own usb cables and im not using the esata and the audio part on that device.

tnx in advance

btarunr · May 30, 2012

It depends on how much the 12V rail it's attached to can deliver. Its physical capacity is usually printed on the bare wires.

Frick · May 30, 2012

There's only one 12V rail anyway so in theory you could pull 48A on that and 25A on the 5V rail (unless the wires melt first). So yes, it'll be fine.

kajson · May 30, 2012

I was just worried if the one molex cable could handle the power, it says something like " 9j awm 1007 18 awg 300v" on the cable.

I cant get any useful info out of those numbers.

edited system specs

n-ster · May 30, 2012

I think it's something like 120+ Watts (12V 11A), you should be fine

only time I've seen a problem is like with 15 delta fans in chain

JrRacinFan · May 30, 2012

kajson said:
18 awg

A single 18 gauge for how small the run of wire will be, would probably be close to 8a.

Frick · May 30, 2012

n-ster said:
I think it's something like 120+ Watts (12V 11A), you should be fine

only time I've seen a problem is like with 15 delta fans in chain

This site says it can do 16A on short wires but that's probably too much.

n-ster · May 30, 2012

lol yea I wouldn't try 16A o.o I stay at 10 and below

FordGT90Concept · May 30, 2012

Wikipedia says 14 amps at 90 degrees celcius (which is very hot). Using that figure, a single 18 AWG wire should be able to handle 168 watts at 12 volts.

If you reduce that to 2.3 amps given here: http://www.powerstream.com/Wire_Size.htm

27.6 watts 12v and 11.5 watts 5v

Used calculator here: http://www.sengpielaudio.com/calculator-ohmslaw.htm

Edit: I'm going to check the Pocket Ref and see what it says.

18.00 amp @ 86-95F
16.38 amp @ 96-104F
15.66 amp @ 105-113F
14.76 amp @ 114-122F
13.68 amp @ 123-131F
12.78 amp @ 132-140F
10.44 amp @ 141-158F
7.38 amp @ 159-176F

As a general guideline, 18 AWG should not exceed 10 amps (120 watts @ 12v).

Edit: Keep in mind that the majority of 12V power is dedicated to the CPU (via EPS12V and P4 connectors) and GPU(via PCI Express 6- and 8-pin connectors).

de.das.dude · May 30, 2012

it will be fine. but that wire may get hot.

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how much power can a molex chain handle?

kajson

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