Hacker News Reader

Comment by jdenning | Hacker News Reader

My measurement technique was extremely simplistic - how much wall clock time does it take to do this computationally-intensive task. It ran faster with ice water, and even faster with the liquid nitrogen (until it died from condensation).

I truly don’t understand why this anecdote seems to be offensive - but let me assure you, I’m claiming no scientific discovery or prodigious understanding of cpus here.

It was neat - computers, liquid nitrogen, color charts.. in the early 90s. That kind of shit got you scholarships back in the day.

View on HN

I think it's because CPUs don't run faster just because they're colder, they run faster when you overclock them. Often to get them stable at higher clock speeds you need more voltage, which at some point demands more cooling to mitigate that.

AFAICT doing interesting but ultimately trivially complicated stuff as a youngster can still result in scholarships etc, Ahmed Mohamed comes to mind.

Perhaps that generation of cpus was very insufficiently cooled? This is before people even really put much of a heat sink on a cpu. The code did run faster with ice water, and faster again with liquid nitrogen. It was a high school, county-level science fair. I don’t know how things stand today, but at the time “will a computer run faster with better cooling?” was a perfectly acceptable level of scientific inquiry for a 14 year old.

I’m truly sorry if my childhood anecdote has inadvertently spread misinformation on this topic :)

People get upset when their understanding of the world conflicts with evidence, especially the scientifically minded.

I mean, this tends to be true, but what evidence are you referring to?

The evidence relayed by the person I replied to, that as the chip was cooled the performance increased.

Alright, that's an interestingly chill take on 'evidence'.

Never has someone described my personal epistemology so succinctly!

the singular form of evidence is not anecdote. I think it's an interesting conundrum myself. as others have pointed out, the story as it was told is not consistent with the physics and current knowledge of what things were like in those days: CPUs did not yet do thermal throttling and simply cooling a CPU from that time doesn't make it go faster.

somebody else mentioned the possibility that the cooling did something to the crystal oscillator, but I think there are another two explanations that either alone or in combination might explain what happened: unreliable narrator (OP was very young when the memory was formed) and external influence - his dad or teacher might have done the overclocking which might have been beyond his understanding and therefore notice at the time.

either way there's no reason to take anecdotes uncritically.

> the singular form of evidence is not anecdote

It is in Bayesian reasoning.

that's right, and you don't just update your posterior to match the one dodgy data point at the expense of decades of evidence.

That’s right. Did somebody investigate the same thing and had different results? Because in this thread there are only theoretical explanations why it cannot be, and not experiments. So in short, there is only one data point.

What conclusions do you believe it is reasonable to draw in light of this? Is your position significantly different from what I said:

> either way there's no reason to take anecdotes uncritically.

> Because in this thread there are only theoretical explanations why it cannot be

No, the explanations are referring to the mountain of evidence based on the physics of the chips and the known characteristics of the chips of the time. That's not theoretical, that past observations.

Show me those observations. Without that your word is just another anecdote.

what would you accept as evidence? does it need to be certified by a notary public?

You know well that a single study about the temperature response of the given CPU is enough.

Those CPUs can fly. Now you have to show me a single study about the flight response of the given CPU.

The logic which you apply here caused several decades and centuries of scientific delays for no good reason.

that's right, we should have been throwing CPUs off a cliff several decades and centuries ago.

Trolling on HN might be one of the stupidest things I've witnessed in a while.

Alternative theory: you also ended up cooling the crystal oscillator, which subtly influenced clock speed.

At any rate, sounds like a really fun high school project!

> Perhaps that generation of cpus was very insufficiently cooled? This is before people even really put much of a heat sink on a cpu.

The 286 came out in 1982 but it wasn't until ~2000 (with the release of the Pentium 4) that thermal throttling was introduced.

From ~1995-2000 if the CPU got over temperature, your PC just turned off immediately. And prior to ~1995 if you ran a CPU without a heatsink it could overheat and destroy itself. We just had to be careful not to do that :)

I am not claiming to be offended, just pointing out the fine line between "Dad's science project" and "Child's science project". It's often blurred.

I get it, I guess I just don’t see the point of trying to determine how much of the project I did myself here and now, 30 years later. It was my idea and I wrote the code, but my dad certainly helped with the physical design, and I think he suggested that I test ice water.

I will leave it to history to judge if I truly earned that blue ribbon

But why?

The lines get blurred because some parents overstep their boundaries to get the child ahead.

Some of us do it so that our kids learn something important, regardless.

>I truly don’t understand why this anecdote seems to be offensive - but let me assure you, I’m claiming no scientific discovery or prodigious understanding of cpus here.

You are stating that providing better cooling to a 286 improved it's performance in the terms of calculating faster.

This is, flatly, false. If you have a 286 clocked at 8mhz, it doesn't matter how much you cool it, it will still run at 8mhz, and still only execute the same number of instructions per clock.

To make a 286 perform more calculations per second, you MUST increase it's clock rate, directly, by installing a faster oscillator. Running at a high clock rate reduces the time each gate in the circuit has to settle to a state, high or low. This can cause the CPU to have what it experiences as "random" gate flips, that will eventually crash it. To fix this, you can increase the voltage, which can force the gates to stabilize faster. This creates more heat. This heat is what more cooling can extract.

In modern CPUs, the voltage, clock speed, and cooling can all be varied independently (within limits) to acheive whatever is desired: quietest/coolest performance, fastest clock, highest performance, etc.

This is not true on a 286.

If the CPU does not crash with a faster oscillator, extra cooling will not increase it's performance.

Reply on news.ycombinator.com