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Old September 5, 2007, 04:59 PM
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Default How to leave the water pump ON for X minute after shutdown

I was wondering how it's possible without an external power outlet pump what most people call a pump switch system.

But I have a DD12V-D5 that connect via the 4 pin power supply connector and I was wondering if there is some equipment that I could connect the pump to it so when I shutdown my computer, the pump will continue to run for like 4-5 minutes or even less but the important part is that the pump will continue to flow so water block donít over heat with the stagnate water.

I was sure I read about one but I am totally unable to find anything related.

Thanks for your help
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Old September 5, 2007, 06:01 PM
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Quote:
Originally Posted by neurobashing View Post
I was wondering how it's possible without an external power outlet pump what most people call a pump switch system.

But I have a DD12V-D5 that connect via the 4 pin power supply connector and I was wondering if there is some equipment that I could connect the pump to it so when I shutdown my computer, the pump will continue to run for like 4-5 minutes or even less but the important part is that the pump will continue to flow so water block donít over heat with the stagnate water.

I was sure I read about one but I am totally unable to find anything related.

Thanks for your help
Hmmm i dont think you have to worry at all, there are no cases ive heard of chips over heating due to the stagnant water after the pc is shut down.

Just go with the normal method and plug it into the PCs cpu.
If you really dont want to, then the only way i can think of is get a second PSU and there is a switch i believe you can buy that turns both PSU's on at the same time, and turn them off at different times.
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Old September 5, 2007, 07:50 PM
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i seen something like what you are talking about it ran the fans for an adjustable amount of time after the power supply turned off but its not on tiger direct anymore i don't know if it would have had enough amperage to run a water pump tho
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Old September 5, 2007, 08:41 PM
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Have something like that control a relay that was connected to a separate PSU for the pump? When the time was up it would just turn the pump's PSU off.
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Old September 7, 2007, 12:49 PM
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Not an issue.

Firstly, it's pretty hard to shut down a computer with the processor at maximum load and heat. So you'll automatically have a little cool-down time simply from the log-off/shutdown procedure. Next, the mass of metal in the waterblock is far greater than the mass of metal in your CPU. This means which means that your CPU will cool down much faster than your waterblock heats up. Lastly, the specific heat capacity of water is over ten times that of copper, which means that even if the waterblock DOES heat up a lot (despite the previous point), the water sitting stagnant in the block will be more than up to the task of absorbing the excess heat output.

The end result - even if your processor is red-hot when you shut it down, temperatures should have no trouble equalizing a few degrees above your coolant temparture. Furthermore, since the hottest part of the equation will be the actual CPU, it's physically impossible for it to become any hotter. Of course, this assumes that your temperatures were acceptable while the computer was running.

All this said, I thought I heard that the M-Cubed/Alphacool T-balancer had such an option... not positive, though. Also not sure if it can handle a D5 pump - those pull over 30 watts, don't they?

Another (weak) possibility might be to install a beer-can capacitor in-line to the pump, which might let the pump to run a short time after the power was cut. It would delay the pump's start-up by an equal amount of time, but probably not enough to cause any problems. Never seen it done, though, and I'm not sure if the electrical circuit is broken or not when the PSU shuts down.
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Old September 8, 2007, 06:13 AM
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hummm! I am not so sure about installing a big cap for the pump. It will stress the power supply at start up, it is like a short circuit for few seconds. Need to do some testing before.

I wont worry to much about the temp. It take few seconds to drop from 65C to 35C from 100% load to idle...
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Old September 8, 2007, 03:59 PM
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Yeah, I'd be pretty wary of it too. Sticking caps into electrical systems at random can cause all sorts of fun. Been awhile since I did electrical, but I imagine that the 'stress time' and 'how long the pump kept running after the power was shut off' would be roughly connected. So by the time the pump ran for any significant amount of time...

Hey, gotta justify those oversized PSU's somehow, right?
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Old September 9, 2007, 11:40 AM
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I agree this is probably not worth the bother but I also think it would be cool just for keen gear factor. If you go for it, you are going to need a separate power supply to run the pump. If the computer is off the power supply will be off too.

If you switch to a lines powered pump there are products available that will help you. Look at the "Expansion Slot AC Relay Switch" at FrozenCPU for an idea about what is available. I know I have seen some that provide the delayed off feature you are looking for but I can not find any links right now.

You could use a 12V wall wart to power the kind of pumps that usually run off the computer power supply. You could install a switch to manually turn it on and off but I figure it would be easy to build a simple control circuit that would sense when the power supply is on and run the pump and keep it running for some time after you turn the power off; this is a simple latch with a relaxation timer. Do you have a community college in your area? You could talk to some of the students in the electronics courses and I bet they can put something together for you.

Keep searching and maybe you will find a retail option.
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