Why CPU GHz Doesn’t Matter!

There is a lot more to IPC than just clock speed, so we took two AMD CPUs with the same core count and similar speeds and pitted them against each other. How well will they perform when underclocked? The results might surprise you!

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MUSIC CREDIT
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Intro: Laszlo - Supernova

Outro: Approaching Nirvana - Sugar High

CHAPTERS
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0:00 Intro
0:57 The Test
1:59 5600x Faster, Why?
3:10 The Takeaways
4:15 If Not GHz, Then What?
5:15 IPC
7:16 CPU Design Factors
8:40 The Solution?
10:10 Outro

[MuitoDaora]

My wife says that size doesn't matter but I say you can do more work at a given frequency.

[HarryUK]

Does CPU GHz matter? No, but yes. Maybe.

[zowbaid]

Mad respect for sharing the names of literally every competitor at the end there.

[alekimura]

In 2008 a professor in my engeneering degree proved with math using the light speed that the cpu coreclock won't be going nothing crazy in the following years, 14 year later, our home/pro cpu's really stayed around the same clocks...

[MiisterShane]

I love how any question related to PC components can be answered with "it depends"

[richardskinner]

The analogy I've always used, is that if CPUs were cars, comparing clock speed would be like comparing RPM. 10, 000 RPM is quicker than 5, 000 RPM, but gearing makes all the difference.

3:30 There’s also this pesky thing, the speed of light. At 10GHz, the distance light (and therefore the maximum anything can go) can travel in a single cycle is about an inch. That would really complicate design and require much smaller, denser, board designs.

[mustang]

I've always used the toll booth analogy.

I'm not sure how accurate I am, but I've always said clock speed is like how fast each car can get through a booth, your cores are how many booths you have, and your threads are how many lanes you have.

Depending on the process that goes through, you could potentially only be able to utilize a couple lanes regardless of how many you have (like if only 2 lanes are open that day) so speed matters a lot more than if traffic was able to split up and utilize all the booths.

[szilagyipeter]

Putting that list of tech reviewers at the end just shows again why I love Linus!

[TylerR]

Just once I want to hear Linus call them "Jiggly-hertz"

[Salvirith]

Goodhart's Law is expressed simply as: “When a measure becomes a target, it ceases to be a good measure.”

[wardlabad]

To be honest, I have been watching Linus for like 5-6 years now from the time I built my first PC to today being a major in computer science, and the amount of knowledge I have gathered over the years from this channel is nowhere near what someone can learn in a decade or two. I am very grateful we have people like Linus and his crew nowadays teaching this information for FREE on the internet for people to have a broader mind and understand some things more than what is just advertised for the general public to know. With all due respect to Linus, the Canadian guy over here I understand just why he is so successful and how much work, information, and investments he put into this channel to make it comparable to real-world education.

[caddilacbob]

It's funny how they're basically so complex that the easiest, most efficient way to calculate their performance is to just run them. And we can't even agree on what we're trying to measure 😅

[FrantisekPicifuk]

I'll just leave a shout out here to the guys at Gamers Nexus and their unending dedication to push the envelope of proper testing methodology and journalistic conduct.

[scotthook]

For us car guys and girls,

GHz = RPM

IPC = torque

Core count = amount of cylinders

Logical cores = SOHC Vs DOHC (hyper threading enabled vs disabled

CPU Cache = turbocharger

Amount of CPU Cache = turbocharger boost pressure

[Dervraka]

I remember back in the 1990's, MHz (and later GHz) was the big bragging point (HA! my i486-50MHz is way better than your i486-33MHz). Then somewhere around the early 2000's it just seemed to stop mattering, ads stopped promoting it and people stopped talking about it. I always wondered the reason it kind of became a non issue.

[TheRishi]

As a computer engineer, this video was spot on. A lot of the topics mentioned in this video prefaced all the cpu architecture classes I took. Nice work LMG!

[watercannonscollaboration]

I first thought the “retro” part of the retro tshirt was that no one can get a GPU, instead of the retro artwork style

[DaroriDerEinzige]

So basically, CPU GHz is kinda like the engine size.

Nice to have, sounds good but not really only determines the performance.

[xnetpc]

What Linus is suggesting is exactly what intel and AMD do now and it makes identifying how one cpu performs vs another. Back when CPU’s was called something like a 386/16 or a 486/25, everyone knew 386 or 486 was the processor’s class and 16 or 25 was the clock speed in MHz. CPU’s of this era also had the letters DX or SX added after the MHz to indicate whether the CPU had an integrated Math CoProcessor on the die or installed as a separate chip.
Later, once intel introduced the Pentium class of processor, AMD and other competitors CPU architects became less of clone of intel and began to diverge performance wise. Rather than label their CPU with a lower MHz than intel, AMD and others began to use a number that was supposed to indicate what Intel CPU’s performance they matched, so a CPU may be named C6-266, it was only 166mhz, but the manufacturer would prefer you to ignore that fact and instead focus on the 266, so you can pretend like your CPU is actually 266MHz. Eventually, after intel ditched the Pentium moniker for their processors, they also began using an alternate set of numbers to indicate relative performance instead of MHZ. That is why we don’t have an intel CPU named Core2Quad2.4GHz, we have the Q6600. Same reason we have the AMD Phenom 8320 instead of the PhenomOctaCore3.5GHz. intel introducing the Core i series processors and AMD introducing the Ryzen line of CPUs has only made it more confusing.