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MSI Develops a Heat-Driven Cooler
V!NCENT tips us to a write-up about an addition to MSI's Ecolution motherboard which harvests heat from the chipset to power a fan. The device is based on a Stirling engine. The heat from the chipset expands a trapped gas, which pushes against a piston to generate power. The article contains a YouTube video of how the device works. According to MSI, the device has 70% efficiency.
Because I thought to get 70% efficiency there would have to be a couple of thousand degrees C difference between the hot and cold sides. Or have AMD decided laptops are not their core market for the next generation of chips?
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No, it works best when the temperature difference between the CPU and the surrounding ist highest. Which usually is the case due to the CPU getting hotter.
The Tao of math: The numbers you can count are not the real numbers.
For the perfect anti-Unix, write an OS that thinks it knows what you're doing better than you do and let it be wrong.
True, fans don't draw much power, but they do fail quite regularly due to the electric motor wearing out, or the motherboard's fan power going dead. As a system builder I see those problems all the time. A self-powered non-electric fan would get rid of both those failure scenarios. It's not like your PC is going to stop producing heat all of a sudden - at least not while its powered on and working.
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If it is idle, it is too cool to drive a fan. So fan does not cool it. If temperature raises too much, there is plenty energy for fan, so it cools the chip. What is so hard in understanding it?
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So if you don't own a computer built in the last 8 years what are you doing on slashdot? Every single video chipset has it's own cooling system, every CPU since the Pentium's have had their own cooling fans. High RPM hard drives sometimes get their own fans, Power supplies get their own fans, Plus one giant slow moving fan for the rest of the case.
Every modern laptop has at least one fan built into it. Something tells me your either deaf and can't hear them, or you just haven't cracked up a case in a long while.
i thought once I was found, but it was only a dream.
Peltier modules are nowhere near as efficient as sterling engines. Using a peltier module, you would be lucky to get enough power to light a small LED from the typical chipset to atmosphere temperature differential. They work fine as heat pumps since you've already got a big sink strapped to the hot side, but when you start trying to use them the other way around - to generate power from a temperature differential - their inefficiency shows through.
There is also about a $100 price difference between those two chips. I imagine they are manufactured to different quality standards. The mobile chip probably has less leakage or something to that effect.
You're absolutely correct that an ideal Carnot engine would have to have about a thousand degrees if it rejects heat to room temperature.
Typically what's done in these cases is to compare the efficiency of the engine to the Carnot efficiency. So the claim of 70% efficiency really means that the engine is 70% as efficient as a Carnot engine at the temperatures it operates between. The real efficiency then is n_carnot*n_engine. Their real efficiency claim is therefore probably closer to 4.9%.
But that's not the only convention. Sometimes the comparison is made to the ideal version of whatever cycle they're using. For a stirling engine, I believe the ideal still approaches Carnot efficiency, so that wouldn't affect their claims, but you can see how some shady math can be used to get people excited.
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In the article they referred to nVidia chipsets, and AFAIK they have been unified chipsets since nForce2 (I could be wrong). Motherboards with these chipsets usually have those tiny chipset HSFs that rattle after 6+ months, and I always end up replacing them with passive heatsinks anyway.
But honestly, even though the chipsets can get relatively hot (35C+) passive heatsinks has worked fine for me.
I have yet to own a motherboard that does not have a fan on the northbridge, except for the one where I'd replaced the manufacturers fan with my own heatsink. This product isn't for that $500 PC you bought from Gateway; it's intended for the performance market. This is still kinda dumb, since fans are probably cheaper than heatsinks, and fans are definitely cheaper and more economical to manufacture than this thing. MSI are clearly doing this to grab some publicity after they realised they're being outclassed by pretty much every other manufacturer, even Foxconn.
The problem with the fan isn't that it's electric, it's that it's a moving part, and moving parts wear out. Usually when a fan dies, it's not the electric motor that's wearing out, it's the bearings. The fans use brushless motors where the coil wrapped around the armature magnetically opposes the permanent magnet built into the rotor(the fan part) causing it to rotate.
http://en.wikipedia.org/wiki/Brushless_DC_electric_motor
70% is a lie. A total conversion efficieny beyond 5% is probably thermodynamically impossible.