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Case fan only starts when given a push

Last response: in Components
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April 23, 2006 11:30:05 PM

Hi everyone,

I'm finishing up my first build of a media PC. I'm using an NMEdia case - 200BA. Very happy with it so far. Only one small problem I ran into. There are two case fans at the back of the case. When I finished connecting everything, I turned the machine on, CPU and PSU fans were spinning but not these rear case fans. First I thought maybe I connected something wrong, and then thought, maybe they're not spinning because they're just not needed yet. However, I touched one of the blades and it suddenly came alive. Same for the other. What could cause this? It seems the propeller gets stuck and needs a push to get going.

Second question. The case has some kind of feature where the CPU fan speed can be controlled from a console in the front. There is a temperature LCD and a connector for the CPU fan. Is it better to use this, or should I just plug the CPU fan into the motherboard? I can't think of a situation where I would manually want to override what the motherboard wants to do.

Lastly, I just want to confirm I did this correctly, because my motherboard manual was not very informative. I plugged the heatsink fan cable to the mobo where it says CPUFAN. There is another header called SYSFAN. Here, I plugged the fan connector coming from the PSU. Is this correct?



Thanks!

W

More about : case fan starts push

April 23, 2006 11:54:24 PM

Quote:
Your fan stalled because it's not getting enough voltage.
Connect all your fans to motherboard and the remaining to 12V line on molex plug.


Thanks for the quick reply. Why do you think it's not getting enough voltage though? I'm using the cable from my PSU which says "fans only". I have the PSU fan control going to SYSFAN on the mobo, and the heatsink going to CPUFAN. Am I missing a connection somewhere?

w
April 24, 2006 12:14:26 AM

Quote:
I'm using the cable from my PSU which says "fans only"

It sound like it's wired to 5V instead of 12V for lower noise.
Check to see it's on red(5V) or yellow(12V) wire.

Yes, the PSU cables that say "Fans Only" are different. They only have two wires, yellow and black. This is my PSU:

http://www.antec.com/us/productDetails.php?ProdID=22430
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April 24, 2006 1:20:36 PM

Interesting PSU.Wierd tho.
Use another molex(one for hdd or optical drive)


I had similiar "problem" not with that psu.
I dig up one big papst cooler form some big adc.
I connect it to 5V but he start spinning after some time.
Belive me you dont wanna hear him on 12V :lol: 
Meyb you will have luck with yours.
April 24, 2006 2:28:12 PM

I did a bit of searching around on this and found other people experiencing the same thing. It seems that a "feature" of this PSU is to automatically control those fans by temperature. When it gets hotter, the fans supposedly spin faster. I'll see what happens after using it for a while.

Thanks for the help.
April 24, 2006 2:53:17 PM

As mentioned the fan is not getting enough voltage at startup. I had the same problem. Most 120mm fans and a number smaller ones require 6V to start. So far I have only found that Antec fans have a low enough (5V) starting voltage.

A number of PSU's with thermal control supply the fans with 12V or something over 7V at startup, then drop to the lower controled voltage. Oddly finding one that does that is hit or miss. Some cheap ones do, and some higher end ones don't
!