how can this be faster than this when it should clearly be the other way around
for years i've been reading comments from people who believe that the faster
the gigahertz the faster the CPU and why shouldn't they believe that gigahertz
also referred to as clock speed or frequency is quite literally a measure
of how fast the transistors in a processor switch so all else being equal
more gigahertz should be more better but all else is not equal and in today's
video we're going to dive into what those unequal things are and just how
unequal they can be we're also going to dive into today's sponsor arazi thanks
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to make sure that our test is as fair as possible both of our cpus used identical
test benches ASUS tough b550 plus motherboards nocto nhd14 coolers 16 gigs
of dual channel 3600 megahertz c14 memory a crucial p5 NVMe SSD and an rtx
3060 xc from evga we're going to have all these parts in our affiliate links
down below well most of them gpus can kind of be hard to find
now for the cpus to keep politics out of the conversation we're going to be using
only AMD branded processors but these principles can be applied to any other
situation where cpus are being compared naturally we started with a full run of
our benchmark suite at out of the box speeds so we can see how the higher
gigahertz 3600 xt fared against the
5600x remember that both of these cpus have
exactly the same number of cores and threads
somewhat intuitively the newer processor does outperform the older one and
sometimes by a considerable margin but why well many modern processors are
capable of dynamically boosting their clock speed under favorable conditions
say for example when they have a really good cooler installed maybe our 5600x is
just a mad CPU frequency boosting machine let's try raining it in and
seeing what happens then at our locked clock speed of 3.4 gigahertz the 5600 xt
still wins in every single test so
clearly then gigahertz is not the only determining factor for CPU performance
but these numbers aren't enough to tell the whole story let's look at gaming if
i only measured average FPS in shadow of the tomb raider and grand theft auto 5 i
might think that a 5600x is only about 5 percent faster than a 3600 xt in the
real world but take something more CPU bound like cs go and these two cpus with
the same core counts running at the same frequencies are nowhere near each other
but then dropping the clock frequency even
further to 2.4 gigahertz it's clear that
the lower the clock goes the slower our
cpus get so what is it does gigahertz
matter or not there are a couple of takeaways here starting with that yes
gigahertz absolutely matters which raises the question then why don't CPU
manufacturers just run their chips at higher clock speeds i mean bring on the
10 gigahertz cpus am i right well
that was the plan actually but higher clock speeds come at the cost
of more power consumption which tends to result in hotter running chips
thankfully though there are a lot of other levers that CPU designers can pull
to improve performance which leads us to our second takeaway cpus or any kind of
processor for that matter gpus phone socs anything
should never be compared using gigahertz
alone it is clearly an important spec and
manufacturers do need to disclose it because it enables us to compare
products within their own families but if you want to talk about an m1 mac
versus an Intel mac or an AMD GPU versus
an NVIDIA one don't even bring it up you
would only be revealing your ignorance on the subject let's talk then about
some of the ways a CPU can differ aside from gigahertz an obvious one is that
they can be designed to process more threads or tasks in parallel Intel was
the first to process two concurrent threads on a consumer chip with hyper
threading or smt while AMD was the first to build a truly multi-core CPU with
their x2 series dual cores that were capable of doing nearly double the work
under ideal conditions the only drawback to additional cores is that they
increase die size meaning cost and power consumption and they can't be used to
accelerate single threaded workloads so in many consumer applications like games
they are only helpful up to a point currently AMD and Intel's mainstream
lineups top out at 16 and 8 cores respectively so we can't keep pushing
core counts forever and expect consumer applications to scale and clock speeds
have been locked in the same range for over 15 years then what have they
changed to really push forward single core performance the simple answer is
ipc or instructions per clock if we
think of a CPU like a mine and each core
like a miner running back and forth doing work the clock speed is how many
times our miner can run back and forth per second while the ipc is how much
they can carry on each load look at the apple m1 for example joe average gamer
might laugh at its meager 3.2 gigahertz
clock speed but when it comes to the real world it performs pretty damn well
like this sexy retro GPU t-shirt from lttstore.com what that tells us about it
is that it has better ipc than a CPU
that runs at a higher frequency but performs the same the problem though is
ipc sounds a lot simpler than it is you can't just
add more instructions to each clock cycle let's go back to our mine analogy
the problem is that our mind contains every single possible type of mineral or
rock and let's say those represent different apps or programs and each of
them requires specialized equipment so
let's say you level up your miner by adding more points to their shovel and
suddenly there's a boost to your coal gathering but sifting for gold well
shovel doesn't help you with that so performance is entirely unaffected
that's how you can see a new generation of CPU come out that absolutely crushes
cinebench but gets the same FPS in games
so ipc is problematic along with clock
speeds and core counts it's one of the most important ways to predict a
processor's performance and yet unlike those other attributes
nobody can agree on a fair and objective way to measure it the way that we
enthusiasts use the term saying things like this new CPU has 20 higher ipc than
the old one can be misleading a manufacturer could easily spend all
their time tuning performance for a single commonly benchmarked program like
geekbench or cinebench when that wouldn't be representative of the real
world experience of using it though AMD and Intel also throw the term around in
this way when it suits them so i blame them now there are major CPU
design factors that can the real world performance of a high ipc CPU
that's tuned for a particular benchmark let's talk about waste going back to our
mine analogy adding cash to a CPU is kind of like making easy piles of our
minerals or data that can be shoveled and carted out of the mine more quickly
the bigger the pile the more likely it is that you can just fill up your
wheelbarrow and off you go on the other hand if there's
nothing in the pile the miner has to go deeper into the mine or to the system
memory to retrieve it that's going to take longer then there's the branch
predictor it is kind of like mine supervisors who attempt to proactively
communicate which minerals are going to be needed in the near future rather than
just having the miners wait around for an order CPU designers can dramatically
improved performance with accurate branch prediction but the logic for it
takes up space on the CPU that could also just be used to add more miners so
it ends up being a delicate balancing act speaking of the physical layout of
the course imagine if our miner parked their wheelbarrow right next to the
mineral heap instead of five steps away and carried it like that CPU designers
are always looking for ways to make each load more efficient and sometimes the
actual physical proximity of CPU elements can be a big difference maker
so an obvious solution to this problem then is to stop using gigahertz stop
using ipc and rather use a broad industry standard set of real-world
tests the problem with that is if we're looking at real-world benchmarks we end
up with real-world messiness including politics between competing brands who
would each naturally prefer tests that favor their own products this is why to
this day we still need reviewers lots of them so that you can see a wide variety
of different methodologies and test suites and how the product that you're
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Linus and use code Linus as always thanks for listening folks i
hope it helps you make the right choice next time you're looking to upgrade if you enjoyed this video hey give a thumbs
up and make sure to check out is 4 core still enough you might be surprised by
the results they are only helpful