cooling fans

[Paul Block]

Can anybody tell me if they know of software or hardware that will allow me to let my cooling fans run after windows shuts down?

[Joleen]

Sure.  Open the case and point any plug-in fan inside.

[Computer Hope Admin]

Other then Joleen's suggestion there is no way to have the fans continue to run after the computer shuts down because the power is turned off.

[Joleen]

In a pm from our esteemed Computer Hope Senior, dl65, I was informed that the question was referring to USB fans Paul is using to cool him (not the computer) and how to keep them running after shutdown.

The answer still applies, there's no power to the system so no way to run the fan.

[dl65]

Joleen.......LOL.....I have been called a lot of things over the years.........but never "esteemed" .........Keep up your great posts

dl65  

[Ian Jolliffe]

This is totally model dependant, if you have an IBM it does one thing, a Compaq does something else. Nothing software wise which will help you.

There are voltages inside the computer if it has an ATX power supply which you could connect to, a couple of simple options might work,

Connect a plug in 12 volt DC power supply to the fans and run a cable out of the case. Remember to disconnect the original cables as something will go bang if the computer and power supply is on at the same time.

If you want to be a little smart about it, and reduce the noise of the fans running while the computer is off you could do this

6 volt DC external power supply
2 diodes (IN4001 will work) penny’s each (or around here cents)

For each fan
Connect the negative of the 6v power supply to the black of the fan(s)
Cut the red wire a few inches from the fan, insert a diode with the stripe towards the fan, and reconnect. (Now when ever your computer is on the fan will run)
Connect a second diode striped end to the striped end of the first diode,

The 6v plus from the power supply to the back of the second diode,

Repeat this each time for the fans you want to run, when you turn the computer off the fans will slowdown & run from the 6 volt supply, leave the 6 volt power supply on all the time.

Note some fans can be as much as 350 ma so don’t expect to drive fans of something the size of a cigarette lighter, also cheap power supply’s will produce up to 17 volts even though the case says 6

Have fun

[MalikTous]

This is a variant of something I have often done to reduce loads on a sometimes cranky power supply.

One machine I was running had trouble with noise from fans on the power leads. I connected a two-level 8/12 VDC 2 amp supply to power the 7 fans (ranging from a .08amp GPU cooler to a .31 amp case-top 90mm exhaust) in a case, and added a small (4 amp DC) 12VDC relay to what was powered from a floppy cable. It was wired so that the power supply 12V tap would power the fans at full speed when the PC is on and the 8V tap would run them at reduced speed when the machine was off. The auxiliary linear DC supply only powered the fans and a case light. The noise problems vanished.

Most of these versions are much simpler, and involve just mounting a 12V DC power pack switched from an AC tap by the relay to add about 20w worth of power for fans. The AC is cut off to the auxiliary supply by the relay when the main supply cuts off. The relay can be provided with a diode and capacitor to keep it closed for a few seconds after the power supply is shut down if desired.

If you are overclocking and adding a peltier cooler, an old AT power supply can be slaved to the main ATX in this manner. Power your CDROMs, floppy, fans, peltier cooler, and optionally HDs from the AT power supply, and put a 20 ohm 5W power resistor across the minus 5 volt line, a 40 ohm 5 watt resistor across the -12V line, and a jumper between the PowerGood and +5V line of the AT power supply.

For external fans to cool the operator, buy standard AC desk fans from WalMart instead of overloading your PC power supply.