Adding an additional Chassis fan.

[Mitch Conant]

I am trying to add a chassis fan to blow hot air out the back (top) of my case. I have a slot fan, but I'm not convinced that it is enough. My MB temp is running around 83F and my CPU (AMD XP 1700+) is running around 133-135F.

My ASUS A7V133 mobo has power connectors for 1-PS fan, 1-CHA fan and 1-CPU fan. Here's my question, I want to install the second Chassis fan. Not having a second CHA(ssis) fan power connector, what is the best way to connect power to it?

I don't think that I can just connect the 2 chassis fans in series, even though the cumulative Amperage (2x160mA) and Wattage (2x1.9W) would fall under the max ratings on the CHA connector on the mobo (12VDC/350mA/4.2W). I tried connecting the 2 fans to one mobo connector, but the second fan did not spin up correctly. I shutdown and pulled the connection immediately.

My next thought is to connect them directly to one of the PS connectors (used for drives, DVDs, etc.), but I have questions on how to do that...

The connector coming from the PS has a Black (GND), Yellow (+5VDC I think) and Red (+12VDC I think) conductors. The fan has 2 conductors Red (+12VDC) and Blue (Rotation, if Radio Shack has followed everyone elses standards.

My questions are...

Does anyone know for sure that the Yellow conductor (mentioned above) is +5VDC and the Red is +12VDC?

Is this (connecting to one of the PS connections) a good way to do this? The slot fan connects this way, I assume that the Chassis fan could be connected the same way. If so, where does the GND come from? There would be no accommodation for a Rotation monitoring line (Blue conductor on the RS fan).

Thanks in advance,
Mitch

[david eaton]

The fan has 2 conductors Red (+12VDC) and Blue (Rotation, if Radio Shack has followed everyone elses standards.
If there are only those two wires, then they haven't!
Red is as you say +12v, and the other wire is 0v. (usually black). It can be connected to any of the spare "molex" (4way)power connectors, blue to black, and red to the yellow.

[Fruss Tray Ted]

Dave,
Shouldn't that read blue to black, red to red? Providing it's a 12v fan anyway...

[david eaton]

The Red wire is the +5v rail, and the yellow is the +12, I thought!

yep. just checked inside my case. Red fan wire to yellow, and black ( blue) to black.

[Mitch Conant]

David and "Ted":

Thanks for the input! I have hooked up the 2 additional chassis fans and have lowered the mobo temp and CPU temp by 10-15 degrees (F). The mobo temp is down to 75F (24C) and the CPU temp is down to 116F (27C). They started at 85F and 134F respectively.

I also cleaned up the rats nest of cables in the case. Just like a person, an unobstructed airway is critical <g>.

Thanks for your help! I like this forum, hope I can contribute to someone else to "pay" for the help you've given.

Mitch