Virtualbox v3.0.4. is going way too slow on one core and the slider is grayed out to disallow me from adding my second processor.

I'm not really certain why it doesn't work with 2, I've looked at some sources that say older dual-core celerons may not support hardware virtualization. Does any one know what constitutes 'older' so I can stop trying to figure this out.

On the acceleration tab, 'Enable VT-x/AMD-v' is checked, but grayed out.

  • As a happy conclusion to this question, I put in a Core 2 Duo processor and got both processors to work in Windows 7 and XP without too much hassle. Had to recompile kernel headers or something, but only one step and it really flies now. – Peter Turner Mar 8 '10 at 21:16

The Celeron Dual Core series does not support VT-x extensions on its hardware.

Check the model of your processor against the Intel Processor Spec Finder - it should let you know if your CPU is VT-x capable.

Intel Processor Spec Finder

Also, if your chip does not support VT-x, if I remember correctly, you can only use 1 core, and nothing more.

By the way, you are not going to see a massive speed increase using two cores with an XP VM. I suggest you optimize the guest operating system instead, or giving it more memory.

  • checked for you - in the Celeron family, only the E3300 (2.5GHz, 45nm) and the E3200 (2.4GHz, 45nm) supports VT-x. – caliban Sep 1 '09 at 16:56
  • I just replaced my Intel Core 2 Duo E8400 with friend's Intel Core 2 Quad Q8200 hoping to improve performance of my VirtualBox OSes. But seems like Q8200 doesn't support virtualisation while E8400 did. Such a pity. – Vikrant Chaudhary Jan 27 '10 at 14:52

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