7v

[AOpen]

i saw a post about a guy making his power supply run a 7v rail, yes i have heard about this, but i just want to know why would you do this??

 

[Aphex_Tom_9]

use a 12v rail, and instead of a ground, a 5v. 12v+5v = 7v

 

[four4875]

...i just want to know why would you do this??

you missed tom.

basically, fans run at different speeds basedo n their voltage. more voltage = faster spinning (up to a certain point, then the fan just dies) and lower voltage = slower spinning and slower spinning = quieter. so if one buys a few 80mm tornados that make your ears bleed after a while, they decide to drop the voltage to slow the fans.

resistors or diodes or transistor based circuits could be used but theres variables there. but conveniently by hooking the fan between the 12 and 5 volt rails, the difference is consistant at 7 volts. so its an easy way to get lower voltage, requires no extra parts, and is easily undoable. its just a tactic to get a quieter system, or at least quiet down a fan some.

There is a guide to doing the mod stickied, in this forum.

hope this answers the question

 

[Aphex_Tom_9]

oy! haha. you got it for me.