Case Mod: question on MOBO cpu fan header

Goose77

Senior member
Aug 25, 2000
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Ok, this is what i have done:

I have my 80mm cpu fan connected to the 2nd powersupply. It's a fan that offers RPM monitoring. I saw that my 1st power supply used the ground cable and the RPM cable of the fan to plug into the motherboard header so i can monitor it's RPMs(does not read the RPM in bios, only in OS hardware monitor and does not crash computer). [info ( 1st powersupply is connected to the motherboard only, second ps is powering fans and hdds)] So, i soldered a connection for my fan(thats hooked up on the 2nd ps) in the same fasion (where i soldered wires to the ground and the RPM wires of the fan, then connected the two wires to the proper motherboard header plug and attached it.

This is the problem:

When i go into bios, once again it doesnt monitor the fan speed, but now my bios crashes only when i go into the PC health(no crash in other areas of bios). And again, it shows up fine in the OS hardware monitor software.

What i think might fix the problem:

im thinking that the only reason that it does not work is because the positive led on the motherboard header is not being used. So, I figure that if i put something that will use the power of the header that it might read the speed correctly without any other side effects! OR, it could be that the ground on the 2nd ps is messing with the ground on the first ps, causing instabiliies! (need suggestions)

What i would like to do:

Solder a LED(light) to the positive and negative connections on the header with the fan connected, this way only minimal power is used from the motherboard header and i get proper monitoring from the bios.

why i did this: ( i know its not the best solution, but i like it this way)

So i can set the "shut down if fan fails". I have my computer set up with two power supplies( a 350/250) to reduce the strain on the main ps for overclocking.

What happened was that the cpu fan was connected to the 2nd ps and someone turned it off thinking they would turn off the entire computer. Low and behold, my unique AMD Athlon XP 1600+ that does 1.8Gigs(was @ 1.67 @ the time) got up to and possibly above 90 degrees C. I could smell the silicon burning!!. When i turned on the computer, it was 80 degrees C. This is after about 15-20 sec of cooling with just the fan turned on, not computer. Silicon like that doesnt come around very often, so you can imagine my anger!!!!! Now if you thing that this is unbelievable, read this, It still works!!!! even at 1.67Ghz but now it works at that speed at default voltage. before i had to use 1.82v for that overclock! Now im not pushing it any harder... too scared. I always thought that it couldn't take heat above 90-95c. Man am i lucky!!!


What i need from you guys:

tell me how to solve this problem, and if my solution is a good idea???


thanks all for any help!
 

cheapgoose

Diamond Member
May 13, 2002
3,877
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no, but you can get a new PS. seems like you're creating your own problems.

does your mobo have thermal protection, ie. shut down when temp > x degree.
 

randomboy

Senior member
Aug 18, 2002
668
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Try switching all the fan connections onto the mobo. I used to have an Abit mobo that wouldnt even boot if you didnt have a fan connected to header1 on the mobo. :\
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randomboy

Senior member
Aug 18, 2002
668
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Oh, I didnt read the whole post. I guess its your own fault for a) letting people mess with your pc, and b) making it possible for your PC to be on, but have no cooling.
 

cheapgoose

Diamond Member
May 13, 2002
3,877
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another option you might be able to use is a relay, like the ones used in a water cooling system. so basically, you can not turn on the ps for the comp unless the ps for the fans are on. just a thought.