Virtual box not allowing multicore guests

[Cade]

I am running Virtualbox on a Windows 2012 host with the following CPU: Intel Xeon E5-2620 v3 2.4ghz with 6 cores and 12 logical processors.

However when I go to configure my Virtual Box guest I cannot enable more than one CPU core or a 64 bit guest.

I have checked the BIOS and virtualization IS enabled. Also I had Ubuntu on this server last week and did not have this problem.

I am definitely running 64 bit Windows on the host as well.

[scottgus1]

If your host has Hyper-v enabled (Windows 2012 likely does) you have to disable it and do a complete power-down & reboot to make sure it's disabled (maybe not the power-down but might as well to be sure) for Virtualbox to be able to use VT-x, then 64-bit & multi-processor will work.

[mpack]

@Cade:
See: FAQ: I have a 64bit host, but can't install 64bit guests.

If you want to continue this discussion then please post a VM log file. With the VM fully shut down, right click and "Show Log" in the GUI, save "VBox.log" (ONLY) to a zip, and attach the zip here.