Question about fan voltage (12v vs 5v)

[tigereye]

Fixing up my fans last night, noticed that they didn't seem to blow fully when they were plugged red-red blk-blk (12-12, gnd-gnd). Noticed that the case fan that came with my case was spliced into yellow (5v?), so moved the 12v (red) to the yellow, and left the blk where it was. Worked much better, seemed to get rated dba and cfm.

Not being an electronics guru, I don't 100% understand why. Can someone explain?

 

[cavemanmoron]

someone had moved it to quiet it down uh if i remember that setting gives you 7 volts

i cant find the site that talked about it sorry...

 

[LYHTSPD]

the yellow wire on the molex connector is +12 volts DC, the red is +5 volts DC, and both the black wires are ground (GND)

here is what you do... run your fans at 7volts if you want to tone them down a bit when you are not using them. you may be thinking "How in the heck do i get 7volts!!!". If you hook one of the wires into the 12volt (the yellow) and the other to the 5volt (the red), the difference of the two (12-5=7) will give you your 7volts...

hope this helps

 

[tigereye]

Actually, I didn't want to tone them down. They were running better hooked to the yellow than the red. I thought red was 12 and yel was 5, sounds like I had it reversed. That explains the confusion.

 

[FreeFrag]

It has been suggested to me by a guy in Dick Smith's (Aussie Electronics Store) that you really shouldn't run a fan at 7 volt by using the 12-5 trick. He told me to use a voltage regulator, basically a 3 pin thingy that you hook up the 12 volt lines (yellow, black) to the first 2 pins and on the top pin and the middle one connected you have regulated 8 volts. The thingy (i dont know what it is called) only cost AU$1.50 and once it's in the case etc...it'll look cooler than just having wires stuck in the power plugs. He also said it was dangerous to do it, something to do with if the 5 volt red wire hits a ground you'll get 7 volt or something...i dunno. he just said it's not good.