How cold is to cold?

[Rich.m]

So I was thinking about pulling out side air into my Rad. I use Ek-cryofuel. It says it freezes at -3C. For about 1 month of the year we have temps around -40C to -51C. My CPU and vid card runs at average 27C. Soo, my question is, for this month out of the year, would the CPU and vid card off set the -40 to -51C, as in stay above 0-C? Also, it's a 480 mm rad. Not sure that makes much difference.

[Shimejii]

Goes by room temp not outside temp. If your room is -40C its time to get out of that room.

[da na]

Seems fine. Plus it's probably not below freezing in your home?

[dj_ripcord]

How are you routing that cold air? Cold surfaces will condense water out of warmer air. If you're not careful, water could condense on tubing and drip into your PC.

[Windows7ge]

I'd worry more about the point at which condensation forms than the fluid freezing. You would see moisture forming on the tubing and blocks inside the PC before the fluid in the rad froze.

 

Unless you put the entire computer out there I wouldn't attempt this. If you have an attached garage that stays above freezing though you might consider putting it in there?

[Rich.m]

Ohh I see I need to clarify. I want to duct out side air through the rad and back outside. No the room would be normal house temp. Lol. Yes the temp being to cold and condensation was the concern, and fluid freezing. I'd imagine there's an equation of some sort that says -40C + 27C / by 2 = -08C. I don't know if that's a good example of what I'm after for equation.

[Guest]

2 hours ago, Rich.m said:

Ohh I see I need to clarify. I want to duct out side air through the rad and back outside. No the room would be normal house temp. Lol. Yes the temp being to cold and condensation was the concern, and fluid freezing. I'd imagine there's an equation of some sort that says -40C + 27C / by 2 = -08C. I don't know if that's a good example of what I'm after for equation.

...... No, But I think perhaps I understand what you're trying to convey.

 

So BTU in and BTU out. You want math and figures.

The problem is the numbers are in constant change.

Yes the ambient temps will still effect the PC, but much less with chilled air being pulled in.

Also that air will dissipate to your room and decrease the ambient room temps. The air must exhaust the case somewhere right?

 

We can use the Cpu TDP rating. This is an average number that's calculated to an average over the life of a processor and helps engineers build an air cooler to dissipate the heat.

 

105w is 360 BTU an hour. 

The math problem starts here. How do we convert an outside temp to a BTU? 

 

Well I used a calculator for home heating and air conditioning.

I asked for 1ft by 3ft by 3ft enclosure with lots of leaks. About 40BTU is all it would take to bring the temp to 1c. 

(The calculator only allows positive numbers unfortunately)

But Never mind that, we'll guestimate. 

 

To bring temps to -50, I would say at least 160w or 545 btu/hr. (If where an A/C maching)

 

So if the weather could be measured in comparison to running an A/C unit, or with temps that cold like -50c comparible to Dry Ice..... not quite as cold....

Cold air in at 545 BTU through the case and rad, lots leaked..... I'm measuring above the radiator out the window..... 

 

Liquid good to only -3c

Warmed up and moving maybe good to -20c. That's being generous actually. depends on flow rate. Some more numbers to throw into the mathmatics of it all...

 

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TLDR?

Just stick the entire PC out the window and go for it. That was my first attempt at chilling without outside air actually. PC wouldn't boot inside, so I balanced it on the ledge and closed the window on it. side panel off, facing outside. Worked pretty good. Got that old Athlon to hit over 3ghz.

 

 

I think you'll freeze the liquid in your loop if the Cpu ever goes idle. This will stop pumping and the Cpu will over-heat. (prediction)