Quote:
Originally posted by unregistered
no Ben
all of the heat IS taken away (if equilibrium is attained)
you have forgotten all that has been discussed about gradients, what they are, why they exist
search here, search google
but understand gradients - or you're drifting in the flow
or read - with deliberation and understanding - Cathar's thread
its in there too
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and as usual you're right
Ok, let me try again, with the gradient in mind...
CPU heats up to 300+deg C, with no cooling whatsoever (and burns up). That's no (zero) steps, in myv65's analogy
.
If we add a heat sink (no fan), the purpose of which is to spread the heat then release it, CPU temps climb very high (100?), and the CPU burns up.
If we put a fan on top of the heatsink, the cpu will remain operational. Temps range from 45 to 60 deg C (roughly, depends on CPU).
If we replace the coolant (air) with a denser one (water), the temps drop to a range of 30 to 40 (roughly).
The purpose of all this is to demonstrate that the internal temperature will vary, according to the cooling solution. The heat generated is completely dissipated, in every case, where the balance point has been achieved, i.e. the heat generated is equal to the heat dissipated.
If we supercool the coolant, temps can hit freezing, but that falls outside of the original question: what's the best we can achieve with Alu/copper?
The best what? Best temp?
The closer we get to the heat source, the lower the potential temp can be achieved.
Sidenote: ok, so if we're getting closer to the heatsource, and we're still dissipating the same amount of heat energy, why is the core temp going down? Are we dissipating more energy? No. We're taking away the buffer zone, the heatspreader, which is allowed to retain a certain energy level, as it's transfering heat. This energy level stored, is what dictates the resulting temp. Given that Alu will store less energy, wouldn't it be best? no, because it can't dissipate the heat well enough.
The problem is this: the heat source is
within the core, and not at the surface of the core. What that translates into, is that there will always be a buffer zone between the actual heat source, and the coolling solution. In other words, it's not possible to cool down the core to ambient (at least not without supercooling).
So what's the best temp we can achieve?
The answer is: what's the best temp that can be achieved with direct die cooling?
BillA: we need another one of your c/w graphs, at different flow rates, for direct die cooling, with a cooling solution normalized to 20 deg C.