It's how cores are defined Intel and AMD have different ways to define what a core is or how instructions are processed through the cores, but the reality in this case is that the AMD 8300 series of CPUs are recognized has having 8 cores (threads are another issue...lol)
The thing you will find is that raw CPU performance isn't as big a factor as you might think, yes, performance is important to the overall picture but it really comes down to resources that can be split and allocated between the host and guest, clock speed isn't as big of a issue and the advantages of faster cycles vs more cores the more cores will win every time in this application.
It's like I said yesterday, you want the available resources to give the guest that relates or is the same amount of resources that you would give Windows running on bare metal, so if you give 8 gig of ram to your guest and the recommended amount for the OS or a given game is 16g then you have created a problem by short changing the guest, will it run?, sure it will, will you get bare metal performance...nope!
Another thing to consider is the allocated space you give the guest to use and is that space a separate drive or is it a partition of another drive, while both will work a separate drive is the preferred that is big enough to house your guest OS and in the case of Windows create a large enough swap file to be happy.
I've said this before but it needs to be said again, when running this type of setup you are creating two computers in one box, you need all the resources for both machines that can be divided up to give each what it needs to be happy, robust and stable, and while Linux is happy to run on minimal hardware and resources Windows isn't the least bit thrilled to be ran on anything but robust hardware and lots of resources, it's not known as a resource hog for nuthin'.
Then the last piece of the puzzle is the host OS (linux), not every Linux distro has the ability to run KVMs in the same stable state as others, while this is getting better distros like Fedora or OpenSuse have better more up-to-date support then some of the Debian based distros like Ubuntu and that's not that they won't work because they will but they require extra effort in the form of configuration and patching which isn't a big deal most of the time.
But the bottom line really comes back to your hardware, the amount of resources you have to share and where that falls in the recommendations of the guest OS and any software you want to run on that OS, give it what it wants and then a little more for margin, growth, and that weird game that taxes the hell out of a Windows environment on bare metal and you can achieve your goal.