Only one processor shows up in Windows 8.1 Guest

[Faraclas]

I am having a problem where only one processor shows up in the windows 8.1 Guest. My system has an i7 Haswell processor and in the VirtualBox guest settings I have selected 4 out of the 8 under the processor options.

How can I get the guest to use multiple cores?

[scottgus1]

Windows 7's Task manager can show each core separately or one graph for all cores together. Have you checked whether 8.1's Task manager has such a setting?

One thing to remember is that your host has four physical cores, hyperthreaded, which shows as 8 logical cores as interpreted by Windows. Hyperthreading doesn't count when assigning CPUs to a guest. You should not assign all cores to a guest, or the host may choke one day. So the max you can safely assign to your guest on your host is three, and likely two or even one may suffice.

[loukingjr]

Check the Device Manager in Win8.1.