Cold plate thickness for air-cooled TEC

[soil]

I do check the front page this time

QUOTE

UPDATE 1/8/01: Some Application Notes

Gabriel Rouchon of Swiftech was generous enough to share his thoughts about some general cold plate guidelines based on the years of their testing:

"Air cooled TEC's require thicker cold plates to move the CPU as far away as possible from the hot side (the heat sink) and reduce parasitic heat radiated back by the heat sink towards the cold side. In that case, cold plates are actually referred to as "spacer blocks". We use copper blocks as thick as 1/2" for this.

END QUOTE

I'm now using a 3/8"x4cmx4cm (HWL) copper cold plate. Want to know what will happen if I use a 1"x 2" x 2" or 2"x2"x2" copper block instead. As this is pretty inexpensive buying from metal shop so I don't mind buying a larger one. I suppose it works like a thermal buffer or reservoir so temp fluctuation can be minimised. My CPU idles at 16C and can go beyond 40C under 100% load gradually. I suppose using a larger plate (block) can extend the time for it to heat up. Probably need foam and masking tape to wrap it up? May also need a shim to avoid the 1 lb block crushing the die? And something to support the mobo on the bottom

Anything else I need to know? oh yes I'm uising desktop case, no worry, and don't move it around

thanks

 

[soil]

a 2"x2"x2" copper cube has 6 surfaces, one is for the CPU, if the 5 remaining surfaces can be for 5 Peltier coolers, if 150W each, maybe minus100C can be reached, assuming anti-condensation measures are implemented. Then one dedicated 0-12V 15A power supply for each Peltier...too extreme...but adding one more maybe more feasible

and the cuble will cost less than US$20 from a local metal shop...

edit: yes, 5 water-cooled TEC

 

[Tecumseh]

If you want to go with 1 inch thick cold plate it wont hurt
a thing. Going to 2 inches wont help a bit over the
1 inch plate as far as cooling. The thicker plates will dampen
your CPU temperature fluctions. I personally would
go with a half inch thick CP for this **air** cooled case.

 

[soil]

would a 2" thick cold plate slow down the temp rise of the CPU more than a 1" does?

as the incremental cost of one more inch of a copper plate is minimal

 

[Tecumseh]

While is is interesting to think of transients, you must
design for steady-state. To answer your question: Yes,
a 2 inch thick block would dampen the rate of change
of your CPU temps somewhat better than a 1 inch block.
I really can't see a good reason to go over an inch,
however. If it makes you feel better, go for it.

 

[soil]

While is is interesting to think of transients, you must
design for steady-state.

Yes, I actually have been wondering why the temp keeps rising, even after using Peltier. Why are there more heat generated than dissipated? Insufficient heat dissipation?

 

[soil]

got it from local metal shop, 50mmx60mmx50mm, 3lb & 1oz, US$2/lb, totalled US$6.3, price of an Intel stock heatsink

a lot of lapping...maybe I just lap the top (TEC) and bottom (CPU)plates only

 

[Tecumseh]

Yes, I actually have been wondering why the temp keeps rising, even after using Peltier. Why are there more heat generated than dissipated? Insufficient heat dissipation?

Yes, insufficient heat dissapation. At what rate is the
temp ramping up?

 

[soil]

Yes, insufficient heat dissapation. At what rate is the
temp ramping up?

about 1C per minute under Toast, I don't want to use the really loud fan and I suspect the overclocked and over-volted PIII dissipated more heat than rated so it may need more than a 75W peltier...Hope the copper block can really slow down the temp increase...

 

[Tecumseh]

Soil, I just read your sig. Is it true that you are air-cooling
the TEC? If so the problem make come down to
1) insufficient clamping force between TEC and HS
2) not enough HS.

What is the rating of your TEC? You know very few
people air-cool a TEC. For a maxed out P3 that is
right on the edge.

 

[soil]

Is it true that you are air-cooling the TEC?

Yes

If so the problem make come down to
1) insufficient clamping force between TEC and HS

No, very tight, that's the water-block screw type

2) not enough HS.

could be

What is the rating of your TEC?

I suppose 75W, not sure though, but if it reduces the idling temp to only 16C it shouldn't be that big

You know very few people air-cool a TEC.

Nah, it's starting from T-Bird that Peltier can't be air-cooled anymore, so far it's okay for Intel, and I am not seeking super-cool, but ~15C fixed

For a maxed out P3 that is right on the edge.

Yeh, very marginal