why does a amd fx 8350 have 8 cores?

It's a convenient number...

A lot of programs that need heavy maths/computing power such as for 3D modelling, video editing & rendering etc. will use all available cores in a computer.

Many games now also use all cores - and for the ones that use eg. 4 or 6, the others allow the operating system, background tasks to be run without stealing time from the game on the cores that it is using.

"Rage" (id software) from back in 2011 was one of the first games to use all eight cores in a CPU that had them - see the graph on the screenshot below. (Ignore the bars above, that's CPU load while taking the screenshot & not while running the game). That's from an older machine with an FX-8320

Making single cores faster is difficult and expensive; spreading the work "sideways" instead gets more done for lower cost.

That's why "Supercomputers" use massive amounts of cores to do the work they do, eg. a Cray XK7 has over 18,000 16-core AMD Opterons, giving almost 300,000 cores...

Think of extra cores like adding extra lanes to a road; with a single-track road, everything runs at a certain speed as long as there are no stalls/delays.

Make it 8 or 16 lanes wide and you get far more traffic through, even though all lanes are still running at the same speed. Any one or two (or more) lanes stalling have little effect on the overall throughput, rather than catastrophic.

The 8 core FX-8350 can do twice the work, with appropriate programs, as the 4 core FX-4 equivalent.

https://www.flickr.com/photos/robertjenkins/838078...

You can see why after looking at these comments.

It starts with a lack of understanding of multi-core processing. People think "Bigger numbers are better!" in computing, so companies find ways to exploit that misunderstanding and sell more.

A bigger reason though, is AMD hasn't figured out how to make their processors run faster since the FX series. They wouldn't sell chips at all if they didn't have good benchmarks, so they doubled the number of cores as a way to keep up with Intel's chips.

There are times that 8 cores is useful. More programs and games are starting to make use of those extra 4 cores, but it's very complicated to coordinate instructions between 8 cores when programming, so usually fewer faster cores is better so the computer spends less time sorting data between cores. But if you have one of those programs that can use 8 cores, the FX 8350 is a nice bit cheaper than it's Intel counterpart.

Direct X 12 basically makes the video drivers support 8 cores, which will help spread the load, and there are games coming out that can make use of those cores. I'm sure it's something that's going to become mainstream eventually, but right now Intel's chips do better with only 4 cores so programmers stick with that because it's so much easier to manage.

EDIT:

Just to mention, something that confuses people is if you watch your CPU usage in Task Manager it will look like each core is being used a little bit. That's not multi-core processing. For a single core program, Windows just sends the next instruction to the core with the lowest load on it. It actually slows things down a bit to be deciding where to send instructions. Back when dual core CPUs started coming out you'd actually get an extra 10 FPS by disabling this and letting the game run on one core.

But, in Windows 10 Microsoft has improved this. Single core programs will often get their own dedicated core to improve performance.

The FX series was from an era where parallel computing was big...unfortunately parallel computing died out in 2009-2015. People simply did not see the use of parallel computing and there are only a handful of people who actually know how to do it properly. Ask how many people have heard of things like TAU at your local university, and there might be only one person who has. Why should they have, when computers continuously became sufficiently more powerful every 2-3 years? Only in scientific applications would you need to know how to parallel program (ironically, the natural sciences, math, and rarely CS). This made the FX look like crap compared to Intel's offerings, but its not that bad if you use it for parallel or multi-threaded workloads (I would take it over Intel in parallel workloads, unless the Intel part is "8 cores" ignoring hyperthreading)** Now in 2016, parallel computing is coming back!

Those cores are there for programs that can take advantage of parallelism. Right now, most programs are just now transitioning to allowing support for 6-8-12-16-24 and more cores. Why? Intel has hit a performance wall like AMD, and the only way to increase performance is through more parallelization. Intel is making a push to move all code produced on its compilers run parallel by default. Microsoft has also begun reworking some software (and their libraries), which is why you might notice better performance as you update your PC (but only if you have a CPU that has more than 2 cores, although Microsoft's methods use threading, so this includes 2-cores with hyperthreading).

**It's important to note that parallel programming != threading; there are other methods to parallel program that offer better performance at the cost of complex memory management. In these cases the FX is still "8 core" although you have to remember it only has 4 FPUs, and an 4 core i7 with hyperthreading will be 4 core.

***The FX is NOT using hyperthreading and the cores are real and can do operations like JMP, MOV, etc. unlike hyperthreading.

It gives the CPU better performance in stuff like CAD, video editing, and animation. The FX-8350 (and all FX in general) is a pretty outdated design that wasn't very good even when it was new, and an Intel i7 (4 cores and hyperthreading) will be a better option.

We are so far into coring, actually about a decade now, more cores the more the merrier. Software may just benefit, you don't need nor should ask such question, more cores may do some good, it'll be a guesstimate how many cores until your computing experience plateaus.

amd is like having a dog sled with 8 dogs, but intel uses 4 horses

It can be helpful when running virtual machines, and it does well with video encoding and a couple other things, but the FX 8xxx's real-world advantages are few compared to a modern i5 or i7.

8 cores are needed if you have an application that can handle up to 8 compute streams at the same time.

DirectX 12 games can make use of all of those cores.

it shall help windows boot up faster and it shall make your computer faster since it has more cores......... it could probably handle 4k which is awesome!!!