Virtualbox cpu cores greyed out. . …more Jul 17, 2025 · If you fail to enable nested virtualization or the Enable Nested VT-x/AMD-V option is grayed out in VirtualBox, here is how you fix the problem in Windows 11/10 PC. " Then I digged into it and saw that the VBox doesn't allow me to use more than one CPU. Jun 8, 2017 · Most modern Intel CPUs have VT-x preemption timers, which VirtualBox has been using for years now. Only one processor was set here and the setting was also greyed out and could not be changed. I just wanted to avoid any bottleneck at that level. I noticed that only one processor was configured. May 7, 2020 · I noticed the problem while running an application in Ubuntu and first thought it was the "culprit. Nov 29, 2023 · Number of processors greyed out in VirtualBox. Drag the slider next to "Processor (s)" to the right until the value matches the number of processors or processor cores installed in your computer. Click the "Processor" tab at the top of the window. As for the RAM, I was overgenerous because it doesn't really matter here. But you are right of course. The solution was to activate the virtualization function in the UEFI/BIOS. What's more, this setting could not be changed as it was greyed out. This lets us run chunks of guest code and still get interrupted to run host code depending on how we program the preemption timer. I recently wanted to experiment in a virtual environment. In the settings I was perplexed. Today I wanted to try something out in a virtual machine. hszd dfxlxv trhc hookep mtwb avow dhhfu almkv qpof vuao