is there anyway to keep the cpu fan cooler ON for 30 more secs after powerdown?or

[anime]

I noticed that on 1.4ghz tbird--the heatsink becoming really really HOT after your shut down your system and fan stop working. I'm just worried if this will have negative effect on the cpu. I think people who overclock their cpu should worry about this problem.

 

[anime]

anyone?

 

[Hammbone]

i noticed mine is pretty hot after shutdown too, dont know how much harm it will cause though. and to answer you question i dont really know how you could keep your fan going after shutdown, bump for an answer though

 

[Aiya]

How about connecting the fans to another power source? You can get cheap 12V power supplies, and as an added bonus, get those with voltage settings (usually 1.5-12V). That way, you can slow down your fans to reduce noise, when performance is not needed.

 

[Shabazz]

Throw a capacitor in between the HSF and the MB.

 

[BraveSirRobbin]

I'm not sure if this idea will work, just throwing it out there for comments:

Could you possibly use an industrial "delay on off" relay?? and install a small separate DC supply (not another computer supply) which is wired to the AC input to the computer "before the off switch" so it is always on. The main (computer) power supply would be the input to the time delay relay's "coil" and the fan would be powered through the additional supply through the relay's "contacts".

When you turned the power off on your computer the relay would time out after a set amount of time as determined by the relay. But, as long as the relay remains on it would supply power to the fan via the "always on" DC supply.

This relay shown in the link below is way over-kill, just showing some of these are out there; only did a one minute search on the web for delay on off relays.

The small DC supply would draw very little current so it wouldn't be a waste of AC since it is always on. It may be a good idea to have a seperate fuse for it though. Also you would have to match up the DC supply specs for the fan (voltage??). Also, because you are powering the fan from the additional supply it won't be monitored (nor powered) from the motherboard (good/bad idea???).

Another way may be to add a large capacitor across the fan and have the capacitor power the fan after shut-down. A little more research will be needed as I don't know the load that the motherboard/power supply is capable of in charging the capacitor (thru a series resistor).

Anyway it seems like a lot of work for this problem (that may not be a problem after all).

Any suggestions?? Good/Bad idea??? Remember, just throwing this idea out there for some others to "think out loud" about this idea (as I have done).

Relay Link

 

[cirrus1]

Adding a capacitor with enough power for 30 secs of fan time might do it. A problem though is that you have to limit the charge current of the capacitor with a resistor. Otherwise you would fry your P/S fuse pretty fast since capacitors draw MUCH current when charging.

The idea with an extra P/S might be a better solution.

 

[cirrus1]

Wouldn't be a problem with the monitor. You could just take the wire and lead it to a fan connector on the board

 

[KouklatheCat]

Get something like a Digital Doc 5 and hook it to a separate junk AT PS. That way you could turn your fans off and on at will AND monitor temps etc. The digital doc (i think) can turn fans on and off based on temperature probe settings.

 

[natopotato]

there is one problem with the capacitor idea. they take time to charge up. it might take anywhere from 10-20 seconds to charge the capacitors. also for 30 secs of fan power it would take some beastly capacitors or a lot of smaller ones. so while you might have 30 seconds after the comp shuts off, you mite have 10-20(maybe longer)seconds when you start up your comp where the fan won't be going.

i personally think the other PS is the best, cheapest and easiest solution. you can pick up a 12V DC power supply for pretty cheap. and like aiya said, you can find varible voltage PS's too. that would give you the most control over your CPU fan.