DL380 Fans - What does what and what controls PWM?

[ajthemacboy]

Hey everyone. I have an old HP Proliant Dl380 G3 (yes I know, I should probably just buy a new one) that, upon startup, says "Fan 7 not present, fan solution not sufficient."

Everyone says this happens with old servers, and if I can't fix this problem I will buy a new server, but I'd like to at least try to fix this one. 

I have replaced the fans and done everything I can to try to fix the problem without replacing the system board. I have dissasembled and cleaned the whole system with no luck.

I had the idea that I could possibly jury rig the fan connection to trick the system into thinking the fan is working, so I dissasembled a spare fan and was surprised by what I saw.

Here are the pictures: http://imgur.com/a/CaQqB

I cannot find any documentation about what wires control what in the system.  

You will notice that there are only 3 wires (red, yellow, and black) going to the fan itself. One wire (black) loops around on itself and goes back out the port. The other two (yellow #2 and green) go to the LED. 

I know enough about fans to know that you can't have a PWM signal on only 3 wires. I also know that the fan spins when the server stars up, but I've read that this problem can be caused by having low fan speeds. I read on one post that someone used a shopvac to blow into the fan to trick the PWM into going high, and the system booted fine. Unforutunately I cannot find that post at the moment or I would show it to you. 

What I need to know is, is there ANY possible way I could trick the system into booting?

Please note: I understand I run the risk of damaging the server by doing this, but I'm not going to spend $40 on a new system board when I can buy a newer and better one for slightly more, so I might as well try to fix it and have it break then to do nothing with it.

[TVVJ]

Hi,

Fan 7 is for the power supply and processor zone.  It may be that the processor might need a fresh coating of thermal paste! (I am trying to make a guess here not completely sure). Reseat the power supply  or try swapping it.

Documentation about internal fan wirings are not available at the HP Support portal.

Regards,

Vijayasarathy

[ajthemacboy]

Hi, thanks, I'll try that, but wouldn't 5 and 6 be for the processor zone? Fan 7 would only get to the power supply.

Judging by this post:

http://h20564.www2.hp.com/hpsc/doc/public/display?docId=emr_na-c00348309-9

If the processor were overheating, the system would suspend for 5 minutes and then shut down. Mine suspends immediately after:

2 beeps

2 beeps + 2 long beeps + 2 beeps