Changing CPU fan from 12 volts to 7 volts: Good idea? Bad Idea?

[Quickfingerz]

I jsut recently learned how to change fan voltage from 12 volts to 7 volts. I like quiet computers. I just recently put a silencer in my power supply (28 CFM my freakin' butt!!!). The system was pretty quiet except for the CPU fan. The RDJD k701 was pretty quiet on it's own. I think it's rated at 28 dB. I still thought it was still loud so I ran the voltage down from 12v to 7v. Everything is much quieter. I can hear my hard driv now. the thing is that i don't know if i'll overheat. I dropped my comp 50 mhz to 850 mhz and droped voltage back to 1.6v from 1.75 that i needed to run 900mhz. Everything SEEMS fine but i'm not sure. Was it a good idea?

 

[Mikewarrior2]

I hate to say it, but I told you that i didn't think the pcPowercooling Silencers were 28cfm.. they are just a tad weaker than Panaflo L1A's, and I have both here to play with... you could have saved a few bucks and gone with Panaflo's from Teamawe.


Mike

 

[Quickfingerz]

Yup, they are more like 24 CFM. They are much quieter than the "quiet" sunon 80 mm fans. I like this quietness though. I should buy a case that that will suppress even more noise.

 

[bigjon]

Is this math correct:

1/2 voltage = 1/2 turn speed of fan = 1/2 airflow???

 

[bigjon]

Actually I think I just answered my own question since the fan speed relies on power which is the Voltage times Current, and when you drop the voltage, the current goes down with it. So 1/2 voltage would result in less than 1/2 the airflow. Right??!

 

[Mikewarrior2]

I think you're right, but he's dropping to 7 volts...


So i think he'll get roughly half the airflow... the only problem is, some fans don't start up while undervoltaged(hte Silencers do, but that's cause htey're small, bigger fans might not).


Mike

 

[Wiker]

RDJD k701 - is this the one you got?
http://millisec.safeshopper.com/45/285.htm
http://www.targetpc.gxnetwork.com/hardware/cooling/rdjd/k701/index.htm

The specs say 17.5CFM/36dBA, so I can understand that you think it's noisy. It's a small fan, 55x55x15mm, so it will get noisy in order to reach that performance. A 60x60x25mm fan of the same performance would be much more quiet. A 60mm 17.5CFM fan shouldn't be louder than 28dBA. Maybe it's possible somehow to fit a 60mm fan on the k701?

 

[Wiker]

BTW: you could use Jouni Vuorio's CPU Stability Test to test the stability of the processor.

http://www.vtoy.fi/jv16/index.html

It will run hours of calculations to check for processor errors/unstabillity. I was just using it to test the stabillity after lowering voltage on my Coppermine. Set the test to run during the night - still was not finished in the morning.

 

[Quickfingerz]

The RDJD uses a 52 mm fan but it's holes are the same as the ones used on 50 mm fans. I know because i connected two different 50 mm fans on it. Running my Athlon at stock voltage and 850 mhz does not heat up very much so even though i have much less CFM, it seems to cool adequately.