4 ms·

Maybe I just need more education in this realm but I’m not sure why a difference in electrical wattage makes it physically impossible for one processor to produ

Maybe I just need more education in this realm but I’m not sure why a difference in electrical wattage makes it physically impossible for one processor to produce a better result than another processor. In the presentation, Johny Sruji seemed to place a bigger emphasis on the reduced power consumption than he did the speed. Saying things like, “this is a big deal” and “this is unheard of”. In my mind, the argument of wattage seems analogous to saying, “There is no way a low wattage LED bulb will ever outshine a high wattage filament bulb.” I have assumed that we’ve been able to make leaps and bounds in CPU technology since the dawn of computers while also reducing power consumption. But maybe there is some critical information I am missing here. I’m certainly no expert and would love to hear more about why the wattage aspect holds weight.

johncolanduoni 6y ago
So there is technically such a known limit due to a link between information-theoretic entropy and thermodynamic entropy, which provides a lower bound on energy usage for a particular digital circuit via the second law of thermodynamics. In simpler terms, there is an unavoidable generation of heat when you "throw bits away" like AND and OR gates do. However we are several orders of magnitude away from that efficiency bound in today's chips, so your analogy to LED bulbs is more apt than you may realize: LED bulbs are still far away from their theoretical maximum efficiency, but they're still a massive improvement over incandescent bulbs. If you want to know more about this limitation, I suggest looking at a way of organizing computation that avoids this issue called "reversible computing"[1]. As I said, it won't be of practical significance for classical computing for a long while, but it's actually pretty fleshed out theoretically. [1]: https://en.wikipedia.org/wiki/Reversible_computing https://en.wikipedia.org/wiki/Reversible_computing
yazaddaruvala 6y ago
(Apologies I’m not sure what your educational background is) Basically, higher wattage makes chips create more heat in shorter time. Heat in general is destructive, like with cooking or with camp fires or when a car “over heats” and stops working. Silicon chips are very detailed and any small change could make them stop working. So the heat applied needs to be below some threshold (i.e. don’t let it get too hot). If the chip needs more wattage it creates more heat and that heat needs a “heat sink” and fan to protect the chip from degrading. Heat sinks and fans require a lot of space, high surface area to volume ratios. Take a look at the PS5 tear down, 90% of the insides are a heat sink. Laptops and phones don’t have a lot of room for heat sinks or fans. Therefore, if the chip can use less wattage then it will get less hot. Meaning it can work better in “fan-less” devices like the MacBook Air and the iPhone and iPad.

johncolanduoni 6y ago

So there is technically such a known limit due to a link between information-theoretic entropy and thermodynamic entropy, which provides a lower bound on energy usage for a particular digital circuit via the second law of thermodynamics. In simpler terms, there is an unavoidable generation of heat when you "throw bits away" like AND and OR gates do. However we are several orders of magnitude away from that efficiency bound in today's chips, so your analogy to LED bulbs is more apt than you may realize: LED bulbs are still far away from their theoretical maximum efficiency, but they're still a massive improvement over incandescent bulbs. If you want to know more about this limitation, I suggest looking at a way of organizing computation that avoids this issue called "reversible computing"[1]. As I said, it won't be of practical significance for classical computing for a long while, but it's actually pretty fleshed out theoretically. [1]: https://en.wikipedia.org/wiki/Reversible_computing https://en.wikipedia.org/wiki/Reversible_computing

yazaddaruvala 6y ago

(Apologies I’m not sure what your educational background is) Basically, higher wattage makes chips create more heat in shorter time. Heat in general is destructive, like with cooking or with camp fires or when a car “over heats” and stops working. Silicon chips are very detailed and any small change could make them stop working. So the heat applied needs to be below some threshold (i.e. don’t let it get too hot). If the chip needs more wattage it creates more heat and that heat needs a “heat sink” and fan to protect the chip from degrading. Heat sinks and fans require a lot of space, high surface area to volume ratios. Take a look at the PS5 tear down, 90% of the insides are a heat sink. Laptops and phones don’t have a lot of room for heat sinks or fans. Therefore, if the chip can use less wattage then it will get less hot. Meaning it can work better in “fan-less” devices like the MacBook Air and the iPhone and iPad.