How to 5v a fan?

[Titan]

I keep bugging ATCC forums because I know how much AT rocks, but I am getting silly now. I am new to this whole super expert cooling thing, and willing to learn much. So I don't keep posting lame questions, someone please give me some links to really good sites that focus on cooling. Now, onto said lame question...

I have a bunch of delta 40mm fans coming in off ebay, that are 20mm thick. I plan to use a whole chain of them for top intake cooling. If they are too loud, I want to 5v them, but I cannot figure out how this is typically done. Keywords like "5v" and "fan" are common so google has not been cooperative.

I have an old old cpu cooling fan with the 2 lines going into a 4-pin molex. Then i realised red goes into the 12v line and black goes into the ground. Since i don't need this thing, could i just swap thew 5v and 12v wires in the molex, and cut the fan leads from my junk fan and use that as a 5v source? That seems like a simple way to 5v something. Also, would it be wise to use that 5v connection for say, 8 40mm fans? My basic EE knowledge says yes, what does your knowledge say?

Thanks!

 

[Titan]

Ok before anyone tells me how dumb and annoying I am, I will do it for you. I didn't read the forum FAQ, I'm still new to this particular AT forum.

 

[Pulsar]

 

[Pulsar]

Use a 12V rail as the power and a 7 volt as the ground. 5 volt differential.

At least, I think that's how it's done.

 

[SWScorch]

some fans wont start at 5V. Switch the red wire and the black wire next to the yellow wire in the 4-pin molex connector for 7V. 12 - 5 = 7.

 

[Mist]

Like yourself, I'm fairly new to this cooling game too, but I have to ask you something: Why do you want top intake cooling?

To my mind, hot or warm air rises, so surely it would be better to have top exhaust fans rather than intakes?

Michael.

 

[xDeLiRiOuSx]

Check out this:

Silent PC Review's site for fan moding

David

 

[0roo0roo]

that or get a fanbus.

 

[RalfHutter]

tkotitan2 - You idea is correct and it's the easiest to implement. Just use the 5V line in place of the 12V line and your fans will be getting 5V. Whether they'll initially spin up is another question. You'll just have to try it and see.

However, using a bunch of noisy little Delta fans to try and suck air into the top of the case is flawed in two ways. First "hot air raises" so you'd be trying to overcome the natural action of the air in the case. Second, those 40mm Deltas are going to be hellaciously noisy at 12V and barely putiing out any air at 5V so they'll either be loud enough to make your ears bleed or going so slow they'll hardly flow any air at all, depending on what voltage you run them at.