Cutting Noise...Fan Wiring...Some ?'s

fubar569

[H]ard|Gawd
Joined
Dec 16, 2003
Messages
1,743
I just got done working on a intermittent overheating problem with my brother's pc (result of dead northbridge fan on his KV-7)...I installed 2 Sunon 80mm fans and one of my old 3Dcool.com 120mm fans and at full power they were way too loud...so i wired them all for 7v by using 5v on GND to the fans and they are virtually silent and still keep the case remarkably cool...

Moving on however, my system sports 2 XP's clocked at 2381mhz with SLK-900A's & 92mm Tornadoes, 2 WD 120GB SE HDD's, & soon to be other high heat producing hardware. it moves so much heat that if i leave my door closed the temperature of my room will rise almost 10 degrees celcius in about an hour...it 2 JMC 120mm fans on the side, 3 80mm fans (2 on back, one on HDD's), my 2 92mm Tornadoes on the HS's, and 2 ADDA 120mm fans on top...and believe me with all of those at full power i'm supprised the damn thing doesn't hover away...i also think it contributed to the death of my powmax 500w PS...lol...

anywhoo...
I'm concerned that in my application wiring to 7v might not provide enough cooling at certain times, and most fan controllers either don't support high power fans or don't have enough leads for me...so i figure if 5v on ground nets 7v, if i used something to apply 3.3v it would be a little closer to 9v which i would feel much better with as an option. i could have a sort of 3 way switch to select 7v, 9v, or full power...but my question is...does anyone have any idea how i could wire this up? i'm not sure if i could use just a switch or would i need a couple of relays or something...also...what would i use to get my 3.3v...could i pull it from the 3.3 going to the MB or could i use something like a Voltage regulator or some other device to drop a feed from the 5v line to around 3v...any ideas? suggestions?
 
I'm fairly certain you won't be able to get the 3.3v off of the mobo/psu bc of the way everything is set up.

Only way I know of that you'd be able to get something closer to 9v is rheobus or a simple resistor. There are a few rheobuses for high power fans, and you can make your own...there is a chip equivalent to the lm317 or whatever the name of it is that is more suited to high power applications
 
Its pretty easy to make a rheostat( or is it rheobus) , or they're cheap enough if you want to buy one. i need to get one myself, sunon 120mm is just way too loud for my tastes...
 
Dont do the reostat. If the power is taken from the fan it is converted to heat, just like putting a resistor in line with your fan. Fan spins at half speed, but the resistor puts out just as much heat as the fan is sucking to move the air. Get a pwm fan controller for $20, They pulse 12v to the fan so the fan can go lower in rpm then if you just put 4v or something on it to slow it down. They also dont shunt power away from the fan in the form of heat. They dont generate heat and as far as the ones ive used, dont even have heatsinks on them. The tests ive seen have had no problems supplying power to 3 deltas on one channel, and you get 4 channels.
 
sounds interesting...where might i aquire one, or read up some more?
 
Back
Top