is molex wired wrong

[evinrude35]

hey guys i was taught red to red always when connecting things on p.c. for power.
why is it that on the antec 900 case fans the wiring does not meet red to red when connecting my molex connectors or am i the only one.
when i plug my molex from psu to the fan molex it is red from psu to yellow fan molex.
is this correct.

 

[Zepper]

Fans almost always use red for Pos voltage, black for ground, yellow (usually, though I've seen white and others) for speed sensor. So if your fan is a 12V unit, then your wiring will be red (fan) to yellow (from PSU). Often fans won't start if connected directly to 5V, so nothing will be hurt if you make that error. Hooking yellow from psu to yellow on the fan can damage your speed sensor.

And welcome to the forums.

.bh.

 

[aigomorla]

Originally posted by: evinrude35
hey guys i was taught red to red always when connecting things on p.c. for power.
why is it that on the antec 900 case fans the wiring does not meet red to red when connecting my molex connectors or am i the only one.
when i plug my molex from psu to the fan molex it is red from psu to yellow fan molex.
is this correct.

welcome to the forums!

Fans can be wired in three ways.

12V is usually the yellow and black next to it.
5V is the Red and black next to it.
7V is the red and yellow.

Seems like your fan is wired for 12V. If its yellow + black.

Dont ask how 5V+12V = 7V

Anyhow, general concesus says you should never wire a fan like that. drawing on the 7V rail which doesnt truely exist i learned damages the power supply.

The 7V cabling setup can usually be seen because its the first pin and last pin on the molex together. Avoid it unless you have a beefy psu.

5V setups, some fans have problems starting at 5V. So make sure your fan does indeed support it if you need it. Another problem is some fans emit a clicking noise when downvolted to 5V.

and 12V, well for most people it would just be overall too loud.

Fan controler is used to fix these issues.

Found an old article from SPCR which should asnwer it more clearly.
http://www.silentpcreview.com/article6-page1.html

 

[Zepper]

Actually, these days ground is common so it doesn't matter but in molex the 12V (yel) and 12V return (blk) and the 5V (red) and 5V return (black) are interleaved thusly:
Molex connector: +5V/12vR/5VR/+12V... In the old days the returns would be striped with matching color.

..bh..

 

[evinrude35]

thanks for the warm welcome.
Well i guess i`m still in the old days.
looks like i`m on the 12v system.
wish i didn`t by this case now.
these fans have a switch on them to slow medium and high.
very quit on low.
well its not sparking or frying or clicking so i must be fine.lol
thanks guys i learned something new.

"my father always said do what you love and you won`t hate you're job"

 

[Zepper]

All 12V fans that come with Molex (PSU style) connectors will connect red on the fan side to yellow on the PSU side. The wiring color codes on these fans came along well before PCs - that's why they are inconsistent. But they are consistent with DC color code standards. Multi-voltage PSUs came along and became common in the PC world had to do something to the color codes for the different voltages, so red for +5, yellow for +12 and orange for +3.3 were agreed on. But you occasionally see some that are different.
. I saw one PSU not too long ago with color codes that reminded me of the bulk candy bins at the super market. I'd have to get out my meter before I'd trust that one - I suppose it was cheaper to use old-stock wire with the weird coloring than to use the standards (more likely to be recent production, more expensive wire) now that the price of copper has gone thru the roof.

.bh.