When I’m shopping for a desktop computer, I hear two numbers constantly: Clock speed (usually in GHz) and core/thread count. What else is there to CPU performance besides these two numbers? What makes a modern CPU more performant than a CPU from years ago, assuming the same core count and clock speed?
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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.
Mmmmm
