Undervolting molex fans

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Undervolting molex fans

Post by Mega.Man » Thu Sep 21, 2006 11:43 am

Hey, sorry, n00b questions :oops:, but in the 7v trick, if i were to have 2X 7v fans and a HDD on a molex power cable would this be ok to ensure that the "5v doesnt go back to the psu" or whatever? :oops: i dont really understand that concept properly (about how extra components solve the problem). Incidently, would this be almost totally safe? (or at least as safe as you can get doing the 7v trick?)

also, while i am looking silly :) how would you go about 'wiring two fans in series' to produce 6v for each fan? i have read around & searched ... but, still none the wiser!

ta in advance

EDIT: after further google searching, i found the answer to the 2nd question (http://forums.silentpcreview.com/viewto ... 867#240867) incase any other new people come across this.
Last edited by Mega.Man on Thu Sep 21, 2006 2:15 pm, edited 1 time in total.

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Post by jhhoffma » Thu Sep 21, 2006 12:39 pm

I always try to split my cables so that all components that require either 12v or 5v exactly (HDD and vidcard) are separated from the rail (or main cable) that I'm running my fans @ 7v from.

I don't want any voltage fluctuation hitting my HDDs or vidcard, since the PSU can probably deal with any voltage irregularities better than they can.

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Post by Mega.Man » Thu Sep 21, 2006 2:16 pm

Cheers jhhoffma, it's just that I'm scared of hurting my new lovely PSU :roll: so is it ok to run the the two 7v fans on a rail together, with hopefully little chance of tears? :)

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Post by justblair » Thu Sep 21, 2006 6:44 pm

It should be fine. The fans draw so litttle amps that the power supply should operate no problem.

If it doesn't? I am a very clumsy "dabbler" when it comes to electronics.. my ambition far outweighs my skill! In my experiance though when I have pushed a power supply beyond its limits even the cheapest have only ever tripped their safety circuits in protest.

Switch it off, wait a minute and switch back on. Its difficult to kill a PSU with a minor mod like this.

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Post by Mav-VRX » Tue Sep 26, 2006 5:51 am

I have a Thermaltake Armor case, and undervolted one of the fans to 7V, and connected the other 3 fans by passing through eachother - therefore all 4 fans are being supplied 7V. It works well, and saves me from spending extra money buying low rpm fans, although a very tiny amount of motor noise remains. I have not run into any problems with the Antec Neo HE power supply doing this.

I have allocated a rail just for the fans at 7V at this point in time, so I'm not sure if plugging a 12V device on that rail would do any harm.

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