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WARNING to 7V fan modders

Posted: Sat Jul 16, 2011 4:57 pm
by Just an ordinary rabbit
Most of you will be familiar with the 7V mod, and the accompanying possibility of damaging the PSU.
However, there is little talk of other dangers, specifically; what happens when the 7v mod is used when the fan's molex adapter also has a male 3 pin attached to the motherboard with a ground wire on it (like this).

I was experimenting with a very similar adapter this evening when I accidentally discovered exactly what happens in this situation:

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As you might expect, this released quite a significant amount of smoke during the 3 seconds it was turned on for, and as my head was behind the motherboard tray at the time (yes, tinkering while it was on :P) I saw the smoke coming out of the PSU exhaust and feared the worst. I was then delighted to discover that I'd only burned the adapter.


Lesson: When mucking about with power leads and plugging them into things the wrong way round; make completely sure that you aren't about to do something regrettable!


Side note: the 80mm Akasa Emperor Blue fan (which is actually a bit quieter than the Nexus) that was attached to said adapter is now making a very noticeable buzzing noise and spinning about 100 RPM faster than it originally did. I', still happy because its quite a lot cheaper than the PSU I thought I'd blown!

Re: A WARNING TO YOU ALL

Posted: Sat Jul 16, 2011 7:33 pm
by jhhoffma
Yeah, 7V mods should really only be done at the termination end of any PSU leads with nothing downstream or daisy-chained except other 7V-driven fans (by using the standard molex configuration).

Re: A WARNING TO YOU ALL

Posted: Thu Dec 15, 2011 7:15 pm
by jcoffin1981
I'm not so sure I understand. If attempting to under volt there are other safer ways to do it, like using one of those in line resistors, or software, or a fan controller. Why use this method?

Re: A WARNING TO YOU ALL

Posted: Thu Dec 15, 2011 9:22 pm
by xan_user
thanks for the warning.
(but that thread title is next to useless...) :roll:

Re: A WARNING TO YOU ALL

Posted: Fri Dec 16, 2011 12:25 am
by MikeC
xan_user wrote:thanks for the warning.
(but that thread title is next to useless...) :roll:
Jumped in w/ a quick title change.

Re: A WARNING TO YOU ALL

Posted: Fri Dec 16, 2011 10:25 am
by Just an ordinary rabbit
jcoffin1981 wrote:Why use this method?
Because it only takes a couple of minutes and doesn't cost anything :)
My motherboard can only control the CPU fan, and I only wanted the fan running a bit slower so didn't want to bother buying a fan controller for it.

Accidentally wiring the PSU's +5V into the motherboard's ground just makes your day a bit more interesting, that's all ;)