How to slow fans to ensure positive air flow???

[Bglad]

I have had some messed up CD-ROMS that I think lost their lives due to dust and dirt drawn in from negative air flow. I now have an Antec 1040. I would like to figure out how to slow down the back two exhaust fans so that they run a bit slower than the front two intake fans thus ensuring positive pressure in the case.

Anyone know a good way to do this?

 

[Lithium381]

if they're the 4 pins, just do a bit of fiddling, and you can bump the voltage from 12 down to 7, by using the 5v(red) as a ground for the 12v(yellow) instead of the ground(black) or just grab a bigger intake fan

 

[mstudd]

What about a 3 watt, 100 ohm potentiometer in line between the power supply and the fan?
You can run 2 fans off it if you get a 3 or 5 watt potentiometer.
I mounted mine in a spare drive bay cover and I can adjust my speeds to whatever I want.
Be wary of permanently switching your fans to 7volts as they may not start up at that voltage.
Checkout this sitefor info on both mods.
Good luck.