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Pre-Cooling CPU before bootup - TEC

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SIBUK

Registered
Joined
Feb 25, 2002
Ok this has been bugging me for a while now...

Currently I have an 800 mhz athlon that is air-cooled and running at 950 Mhz and so the temperature of the CPU never drops below room temperature

BUT if I had a Peltier and water cooling system and my CPU temps were typically below 0, and lets say my 800 chip was then running at 1150 Mhz (which it would never run at at room temperature), then when I turn my PC on and the CPU is at room temperature, surly it wouldnt boot until the pelt cooled things down?

Does this mean that if you have a pelt cooled CPU that you have to turn the cooling on first and leave it for a few minutes while the CPU cools before turning on the PC and booting up? or does the pelt cool down so fast that it doesnt make any difference?

Just wondering :)
Cheers,
Si
 

Tweak

Registered
Joined
Mar 24, 2001
Yes you would probably have to cool the chip first brfore you turn the PC on. I had to do the same thing on my old P2 watercooling project.
 
OP
S

SIBUK

Registered
Joined
Feb 25, 2002
Ok cool, so, idealy, if I was going to set up a peltir cooling system then I would need to create some type of circuit so that when I press my power button, my water pump and second PSU that is powering the TEC turn on, then a timer waits for 30 seconds (or however long it takes for things to get cold enough) before activating a relay which switches on the rest of the PC

sounds like a cool project to me :)
 

Bender

Mysteriously Changing Senior
Joined
Dec 19, 2000
Location
In Thelemac's Basement Eating the Chickens
Hey welcome to Overclockers.com SIBUK.

I have actually been thinking about doing the same exact thing. All you would need the circut to do is briefly short the 2 wires of the ATX PSU to get it to turn on. Once the psu has been on for a while you need it to begin giving power to the rest of the system. You could possibly do this with a relay and some sort of timing circut. Even better yet; have a temp sensor trigger the power on so you can boot at optimal temperature. I still have a few loose ideas in my head so I'll try to gather my thoughts and let you know what I'm thinking. Any ideas?
 

Colin

Arctic Silver Senior
Joined
Dec 19, 2000
It takes about 20 seconds to cool a coldplate below zero. A simple way to do this is install a relay to power the pelt with the computer and hold the reset switch in until the coldplate cools. I recommened something like a Compunurse with a sensor on the coldplate to monitor the temps.
 

soil

Member
Joined
Dec 29, 2001
Location
Sydney
seems like the sequence is:
(1) turn on the PSU for the TEC and a timer circuit (or a thermal sensing circuit)
(2) after say 20 seconds (or reaching xC) the timer circuit via a relay short the power switch of the mainboards and boot the compter

the wiring would be simple, ie, instead of connecting the 2 pins for "power on" in the mainboard to the switch you hook it to the relay (and you just need a small DC relay)
 
Last edited:

soil

Member
Joined
Dec 29, 2001
Location
Sydney
Bender said:
Colin do you know of any timed relays? I'm shure I could make something but it would take some fooling around.

Radioshack probably has a kit using IC555 to control a small relay within a preset delay

edit: ooops Bender you are not asking me:D
 

Diggrr

Underwater Senior Member
Joined
Nov 29, 2001
Just using a relay wouldn't work, it would keep the connection for the power button in a 'made' state, so the computer would cycle back off the same as if you'd used a rocker switch for the power button.
Is there such a thing as a momentary relay?

Use the small 555circuit relay to throw a larger relay that would power on the psu at it's plugin. Mine (abit kt7a-r) has a setting in bios to restart the computer when power is restored, like after a (house)power failure. Does your board do this? If the power supply is switched on, the computer restarts just by plugging it in (not hitting any buttons)?

Just a thought.
 

Bender

Mysteriously Changing Senior
Joined
Dec 19, 2000
Location
In Thelemac's Basement Eating the Chickens
I thlink I found something that can be easily modded to work. Take a look at This radiashack kit. You can probably replace the led with a small relay so it flips the big relay for the system power on. You might have to use a trimmer on the relay to tweak the power it takes to trip the relay. LEDs dont take much juice so you will have to use a lower power relay. Just one question; how does it monitor the temperature? If it has a probe it might just work. You can always take out the junctin and replace it with oneof those probes every mobo comes with.