# [SOLVED] Fan question



## Acuta73 (Mar 17, 2008)

Haven't trolled here in a while, but thinking about a case build for my son (project:Stardust never got clearance for take off from the wife). What I need to know, from people who understand power demands more than I is, can I use a 12" 5 amp automotive fan running off of an 850w PSU? The CFM is insane compared to computer fans of roughly the same diameter (360mm), but can/will the PSU handle it? I would need to change the wiring a bit and mod the mounting, but those things I can do. Other possibility would simply be to go with a 110v-12v wall converter, so all is not lost if this isn't an option.

If this is a go, the project will be: Afterburner..and you'll see why when I WIP it.

Eric


----------



## Acuta73 (Mar 17, 2008)

*Re: Fan question*

Nevermind over all, I just found a 110v AC to 12v DC converter for $15. That solves that. However, I'd still like to know if these fans can be run off of a PSU. The more I think about it, the more I think PSU power is AC..so no..but, I could well be wrong.

I am building a cardboard mock-up of the case, atm. Expect a worklog shortly (need the case done before taxes get back...familiar story?). 

Eric


----------



## grimx133 (Jan 15, 2008)

The power supply takes the wall AC and converts it to DC for the computer components,
anything in the computer that is AC requires an inverter. That's things like laptop lcd
screens and cold cathodes. 
A molex connector from your psu will provide more than the 5 amps you need on the 
+12v. DC, it's good for 75 watts, and the fan draws 60.


----------



## Acuta73 (Mar 17, 2008)

Veeery interesting, thank you for the response!

A 12" fan @ a max of 900CFM beats the snot out of a 360mm fan @126CFM. Run the thing through a rheostat and I should be able to get at least 300CFM at a very doable noise level. Can even get radiator fans with the scythe-edged blades for even less noise.

Not surprised I was wrong about the PSU, and if I'd actually stopped and thought about it long enough, I'd have figured it out. Just glad the amp demands don't go over the limit.


----------

