5 volt question?

anakintjc · Post by **anakintjc** » Sat May 26, 2007 7:58 am

Hi,

Normally red (5v) to red and black to one of the black's is 5 Volt...

But my 120 mm fan wouldn't start then, now i did yellow to red and red to yellow and i kept the both black's, what kind of voltage is that? Also 5V ?

thanks!

tehfire · Post by **tehfire** » Sat May 26, 2007 8:10 am

I couldn't really understand your question, so hopefully I can stab in the dark and come up with an answer...

Using the yellow and black wires from a power supply will make 12v
Using the yellow and red wires from a power supply will make 7v
Using the red and black wires from a power supply will make 5v

It's possible that your 120mm fan didn't start because its starting voltage may be higher than 5v, or possibly you crossed the wires wrong...

anakintjc · Post by **anakintjc** » Sat May 26, 2007 8:15 am

normally from top to down it's : yellow (12v), black, black, red (5v)

This was a male molex connector (from the fan) and i switched the yellow and the red one and connected it to a 'normal' female molex (psu)...

What volt am i on?

psiu · Post by **psiu** » Sat May 26, 2007 8:28 am

If you switched the red and yellow, you should be on 5V then. Some fans may not start at that voltage. Are the molex pins back in all the way?

anakintjc · Post by **anakintjc** » Sat May 26, 2007 9:03 am

yes if i change red and yellow it works (and leave 2 blacks in) ...

When i only use red and black (leave yellow and one black out),
it doesn't work. How does that come?

The fan i'm talking about is the 120 mm fan case from the antec sonata.
Fan Specs:
- RPM 2000
- CFM 79.06
- dB(A) 29.8.
With Fan Only connectors 20.4

I can tell you that the airflow ain't much but doesn't bother me (as long it moves some air to passive vga card).

So at 12V it's 2000 rpm and CFM 79, could someone indicate what the values become at 5V?

ya8282 · Post by **ya8282** » Sat May 26, 2007 9:42 pm

anakintjc wrote:yes if i change red and yellow it works (and leave 2 blacks in) ...

When i only use red and black (leave yellow and one black out),
it doesn't work. How does that come?

As tehfire stated, your fan probably has a higher starting voltage than 5V, therefore it will not start at that voltage.

jaganath · Post by **jaganath** » Sun May 27, 2007 2:56 am

So at 12V it's 2000 rpm and CFM 79, could someone indicate what the values become at 5V?

at a rough guess, ~900rpm and 38CFM (in free air),in a case cfm will be less.