In 2025, there are extremely efficient CPUs from Intel and Apple. Under 5W idle!
The old Intel CPUs were grotesquely inefficient. Every single generation of Raspberry Pi has been well under 5W idle. And just so it's clear, the author is using an old Raspberry Pi 3.
From TFA:
> The RPi 3B’s 19.2 MHz oscillator is physically located near the CPU on the Raspberry Pi board, so by actively controlling CPU temperature, we’re indirectly controlling the oscillator’s temperature.
Also note that the R.Pi can even be further optimised by switching off HDMI.
> In 2025, there are extremely efficient CPUs from Intel and Apple. Under 5W idle!
I don't think Intel has any "efficient" CPU that can go passively cooled at load though. Maybe Apple can do it for the low end SoCs.
The Pi 3 can go passively cooled and maybe even without a heatsink at load, but the newer Pis can't. Judging by the progression from 3 to 4 to 5, they will reach P4 levels of heat in the name of speed around ... 7?
> And just so it's clear, the author is using an old Raspberry Pi 3.
Yes, the author has harder problems to solve than what I'm whining about. But my concern is a bit related.
> The Pi 3 can go passively cooled and maybe even without a heatsink at load, but the newer Pis can't.
The Raspberry Pi 4 can be used without a fan. They are packaged inside keyboards, but both the Raspberry Pi 400 and the Raspberry Pi 500 are passively cooled.
Intel tried to scale frequency up with the Pentium 4 in the name of performance, and it ended up extremely hot and power hungry. Just like some high end CPUs now, but then it applied to every model from Intel.
I suppose you don't remember when a Raspberry Pi could run fine even without a heatsink, let alone active cooling. That's more recent than the Pentium 4.
It's already there really. It's heat output on the 4 and more so the 5 benefits from active cooling. The good news is the pi is practically pointless as a product for most people these days, and vastly better options are available cheaper, so unless you genuinely need the gpio theres little reason to buy one - very much their own fault for focusing on commercial applications but the Pi 5 as a product is practically pointless for a consumer use at this point. An old Pi 2 or 3 which dont need any cooling are very useful still for a range of applications but the newer ones are in a bit of a weird niche where they're overpriced compared to most options.
Thanks for giving me yet another reminder that I’m old. I caught the reference immediately and thought nothing of it, and then this shattered that.
The early ‘00s were a wild time. Intel boldly stating they expected to get the P4 up to 10 GHz, AMD having to assign clock speed equivalence ratings for their chips… I also remember thinking the P4EE was insanely priced ($1000, or about $1700 in 2025 USD), but now we have >$10K Threadrippers.
In 2025, there are extremely efficient CPUs from Intel and Apple. Under 5W idle!
The old Intel CPUs were grotesquely inefficient. Every single generation of Raspberry Pi has been well under 5W idle. And just so it's clear, the author is using an old Raspberry Pi 3.
From TFA:
> The RPi 3B’s 19.2 MHz oscillator is physically located near the CPU on the Raspberry Pi board, so by actively controlling CPU temperature, we’re indirectly controlling the oscillator’s temperature.
Also note that the R.Pi can even be further optimised by switching off HDMI.
https://www.pidramble.com/wiki/benchmarks/power-consumption
https://www.jeffgeerling.com/blogs/jeff-geerling/raspberry-p...
> In 2025, there are extremely efficient CPUs from Intel and Apple. Under 5W idle!
I don't think Intel has any "efficient" CPU that can go passively cooled at load though. Maybe Apple can do it for the low end SoCs.
The Pi 3 can go passively cooled and maybe even without a heatsink at load, but the newer Pis can't. Judging by the progression from 3 to 4 to 5, they will reach P4 levels of heat in the name of speed around ... 7?
> And just so it's clear, the author is using an old Raspberry Pi 3.
Yes, the author has harder problems to solve than what I'm whining about. But my concern is a bit related.
> The Pi 3 can go passively cooled and maybe even without a heatsink at load, but the newer Pis can't.
The Raspberry Pi 4 can be used without a fan. They are packaged inside keyboards, but both the Raspberry Pi 400 and the Raspberry Pi 500 are passively cooled.
2 replies →
Noctua has a cooler that can handle something like 65W-70W CPUs completely passively. https://www.noctua.at/en/products/nh-p1
> I don't think Intel has any "efficient" CPU that can go passively cooled at load though. Maybe Apple can do it for the low end SoCs.
Does the N100 not fit this criteria?
3 replies →
What is this even supposed to mean? What's "the Pentium 4 route"?
I'm an old fart :)
Intel tried to scale frequency up with the Pentium 4 in the name of performance, and it ended up extremely hot and power hungry. Just like some high end CPUs now, but then it applied to every model from Intel.
I suppose you don't remember when a Raspberry Pi could run fine even without a heatsink, let alone active cooling. That's more recent than the Pentium 4.
It's already there really. It's heat output on the 4 and more so the 5 benefits from active cooling. The good news is the pi is practically pointless as a product for most people these days, and vastly better options are available cheaper, so unless you genuinely need the gpio theres little reason to buy one - very much their own fault for focusing on commercial applications but the Pi 5 as a product is practically pointless for a consumer use at this point. An old Pi 2 or 3 which dont need any cooling are very useful still for a range of applications but the newer ones are in a bit of a weird niche where they're overpriced compared to most options.
3 replies →
Thanks for giving me yet another reminder that I’m old. I caught the reference immediately and thought nothing of it, and then this shattered that.
The early ‘00s were a wild time. Intel boldly stating they expected to get the P4 up to 10 GHz, AMD having to assign clock speed equivalence ratings for their chips… I also remember thinking the P4EE was insanely priced ($1000, or about $1700 in 2025 USD), but now we have >$10K Threadrippers.