Ask Lemmy

IPC, or instructions per clock. So how many instructions it can process per Hz. And which instructions it supports. For example AVX512 can speed up bulk data processing in specific applications that support it.

With all these complications the only way to really compare CPUs accurately is to benchmark the programs or games you intend to run on them. Obviously this is not realistic so reviewers benchmark a few varied real world programs, games and artificial tests. Those results usually extrapolate fairly well to other, similar software.

Other people answered how it's measured, but if you're just shopping for a CPU I'd recommend skipping straight to benchmarks. There's a lot of technical stuff involved but if you look at Geekbench/Passmark scores you can easily compare which ones are more powerful.

If you're shopping for a laptop with a specific CPU I'd also look into how much power it uses (in Watts).

• IPC
• Instruction set
• Levels 1 through 3 cache
• Performance per watt, usually measured by benchmarking, gives you an idea of efficiency

Generally, you can assume that a newer CPU with a the same thread count as an older CPU will outperform it.

However, you'd have to keep in mind a CPU is a very complex entity comprised of its cores, its cache, its bridges, its controllers and whatever I'm missing. Intel, for instance, would not make any huge changes to architecture every other generational skip. It's what they called tick-tock. The tick would be a new concept, the tock would be a refined version.

But redesigning the entire chip, ie its lithography, the layout of what is positioned where, all the way down the to smallest detail, will have some effect on performance. It's difficult to quantify, hence the need for benchmarking tools like Geekbench.

Do you know engines?

Clock speed is basically RPM. And core/threads are cylinders.

So a 4 cylinder 1.8L engine at 5k rpms isnt necessarily doing more than a 350 v8 at 4k rpms.

So the numbers do mean something but you can't just pick the one with the biggest number either.

Tomshardware.com isn't what it used to be, but they keep an updated cpu list of how good they are at different workloads.

FLOPS, floating point operations per second.

A CPU, at its basic level, does math and logic. GHZ is a measure of electrical frequency, aka how fast the switches inside a CPU turn on and off per second; it is only tangentially, loosely related to the amount of math and logic per second that the CPU can do.

Like the other commenter said, IPC, or instructions per clock, measures how much "stuff" a CPU can do each time it's control signal switches on and off. More advanced modern CPU's can do more stuff per clock, both because of architecture improvements, and because there are more "cores" (CPU's inside the CPU, basically). And because of the difference in architecture and other behaviors, it's hard to "apples to apples" compare CPU's. I could take a 4 core cpu from 2012 and a 4 core cpu from today, have them both run at 4ghz, and the modern one would run circles around the 2012 cpu.

The better way to shop for modern processors is not to look at nameplate numbers like GHz. Instead you should find multiple independent software benchmarks that can apply a relative number to the amount of math and logic a CPU can do per second, which allows you to accurately compare different processors side by side. Software like Cinebench does this. There are multiple artificial benchmarks that show performance in many different workloads, pick one out that is most similar to what you would do on a daily basis.

Many review sites like tomshardware will also provide additional data, like core temperatures and power consumption under load, to provide a fuller image of what a CPU can do and what its drawbacks might be.

I'd just use benchmarks from openbenchmarking.org and Passmark's cpubenchmark.net if you want to determine performance.

Mmmmm