CPU Cache Importance?

NitroBladeZ · November 18, 2023

I'm trying to build a PC and I'm picking a CPU at the moment and I'm not sure neither how important CPU cache is nor what CPU cache is
could anyone give me a bit of advice?

Tetras · November 18, 2023

It would help if you can give us some context, like what your budget is and what you use the PC for. There are few situations where you would deliberately choose one CPU over another CPU just because of the cache, with the exception of AMD's X3D CPUs, which are better for gaming than even the higher core count alternatives (e.g. the 5800X3D is better for games than the 5950X and the 7800X3D is better than the 7950X).

RONOTHAN## · November 18, 2023

There's a bunch of analogies for this, so someone might give a different one, but this is the first one to come to mind.

Imagine you're doing work from home that involves referencing a bunch of documents. You'll have some right in front of you, some on your desk, some in a file cabinet across the room, and some back at the office. The ones right in front of you are the equivalent of the registers on the CPU itself (what the CPU is currently doing math with), the ones on the desk next to you are equivalent to the CPU's cache, the ones in the file cabinet are the equivalent of the RAM, and the ones at the office are the equivalent of the hard drive.

More cache is the equivalent of a bigger desk, where you can reference more stuff and get more work done without wasting time going across the room to find documents. If you're doing stuff where you only need to reference a few different documents, the bigger desk isn't really going to help, while if you're doing stuff that needs to reference hundreds of different documents you'll need to be heading to and from the file cabinet no matter what, so while the bigger desk is nice it doesn't really help all that much. The workloads where it helps is where you need to reference a lot of stuff, but not an insane amount of stuff, plus the workload and how you work also impacts how it helps, just like how different workloads and different CPU architectures benefit differently from more/faster cache.

I wouldn't necessarily look at the cache directly, since there are a lot of other factors that impact performance than just the cache amount. The only real way to know how it behaves is to look at the benchmark scores. What CPUs were you comparing?