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 Post subject: Hot PSU, is my mobo the culprit?
PostPosted: Thu Dec 05, 2002 7:00 pm 
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Joined: Mon Oct 21, 2002 1:01 am
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Location: Vancouver, BC, Canada
I'd like to undervolt my PSU fan to 7V, but I'm afraid it would overheat. The exhaust coming out is already quite warm.

The question I'd like to throw out is: Is my oldish-TigerMP board to blame. Is it a SilentPC-unfriendly mobo? I hear all these stories about how the CPUs draw their power from the 5V line. Since I've got 2 CPU's, the 5V rail must be working quite hard. Is there anyway for me to find out for sure? Does a board like the TigerMPX improve upon this situation because of its extra power connector?

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 Post subject:
PostPosted: Fri Dec 06, 2002 7:26 am 
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Joined: Fri Aug 16, 2002 11:35 pm
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Location: Amsterdam
I don't think the motherboard is specifically quietpc unfriendly, but I reckon that 2 cpu's generate a lot of heat, and somewhere somehow this heat must get out of the case. Very often the psu exhaust is the only route out, so the air that comes out will be warm at least. Also, 2 cpus will need a lot of power, wich not only generate more heat on the mobo, especially the voltage regulators, but also make the psu heat up more because it has to deliver all this power.
I think it will be difficult to get a 2 cpu system quiet, but it might help if the hot air from the cpus would be drawn out of the case before it reaches the psu, so maybe you can arange it in such a way that a big slow revving fan is drawing the air from the cpus straight out of the case. This will help the psu getting cooler air, but it will not help it generating less heat.
If the air coming out of the psu is significantly cooler then, you could try to lower the voltage of your psu fan, but be carefull that an extra fan in the case sucking air out may case a bit of underpressure, making life harder for any other fan in your system, like your psu fan.
All in all, a 2 cpu system will be louder than a single cpu system, unless you're willing to go for a watercooling that includes watercooling of the psu as well.


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PostPosted: Wed Dec 18, 2002 7:36 pm 
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Joined: Sat Nov 09, 2002 10:12 pm
Posts: 36
Location: Calgary - Canada
My PSU is running a fan at 5V, but I only have a single CPU which is water cooled. The air tempature inside my case is only 4°C hotter than the air tempature outside the case so my PSU runs fairly cool.

The only way I can think of making a truly quiet dual CPU system is water. Dissapating another 40-50W is a lot of energy to deal with inside a small space. However, an external heater core could easily take care of the heat, and more.


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 Post subject:
PostPosted: Thu Dec 19, 2002 1:48 am 
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Location: Vancouver, BC, Canada
Asmordean,

It depends on what your idea of quiet is, but I'm very certain that a quiet & fast dual CPU system can be achieved with air-cooling only. It's taken me a bit of experimentation, and I still have some further work to do, but I believe I'm close to achieving quiet. Quiet as in I can hear the buzz from my monitor and fluorescents over the whine and hum of my HD's and fans. Quiet as I can sleep at night (and I can only sleep in silence).

Granted, though, 5 Panaflos at 6V is gonna be just a tad over 3dB louder than 2 - 6V Panaflos and 6dB more than 1 - 6V Panaflo. I can't argue with you over that.

I'll be able to disclose more later, but my signature below has a brief description of the mod's I've done and the temps I've achieved.

Going back to my PSU - I just bought a multimeter and thermometer and measured the voltage and exhaust temp. My NMB 18cfm PSU ex is at 10.5V and the exhaust is 37C. This was once I removed a restrictive air filter from the duct intake and cut a hole through my Antec door. I will be undervolting to 7V and mounting the fan on the outside of the PSU soon.

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FS: SX1040, PSU duct, TigerMP, 2x1.4GHz, 'Cuda7 120GB, dcupld L1As (6V) (link)


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 Post subject:
PostPosted: Thu Dec 19, 2002 11:56 am 
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Joined: Sat Nov 09, 2002 1:45 pm
Posts: 149
powergyoza wrote:
Quiet as in I can hear the buzz from my monitor and fluorescents over the whine and hum of my HD's and fans.


that's where i'm at now. good to know someone else is in my shoes as well... :lol: the buzzing from the fluorescents are driving me nuts. as of the monitor, i eliminated the buzz by adjusting its brightness/contrast. it seems to make the buzzing sound when the brightness is set low. try to play with it, hopefully you can also find the 'sweet spot' where monitor wouldn't buzz any more. my display is dell 2000fp.

i'm thinking of changing my bathroom fan with panaflo...... :lol: business in silence or choke in the static air.... that's a dilemma..


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