We help IT Professionals succeed at work.

ESXi & 64-bit CPU questions

fred2k3 asked

I have installed ESXi 4.0 on a HP Proliant DL380 G4 server. Unfortunately I don't know if the processors are 32 bit or 64 bit. Does anyone know the easiest way to find out for certain? (The BIOS doesn't seem to mention anything about the architecture)

I have installed Windows 7 (32-bit) on a VM and from the registry HKEY_LOCAL_MACHINE\HARDWARE\DESCRIPTION\System\CentralProcessor\0 it looks like it's 32-bit.. but I don't know if I should trust this since the VM has been told to set up the machine for 32-bit Windows.

I tried installing 64-bit Win 7 and got a message saying it was incompatible with the CPU, but having already installed other 32-bit O/S on the same datastore I wasn't sure whether this perhaps had any baring on the matter... which leads to my second question...

Is it possible (and if so, advisable) to install both 32bit & 64bit O/S on the same datastore? Are there likely to be any adverse affects?

Watch Question

Top Expert 2010
There are a couple tools you can use to check your CPUs:

Top Expert 2010

BTW...yes, you can have both 32bit & 64bit on the same datastore, but if your CPU/BIOS doesn't support 64bit or isn't a 64bit compatible CPU, you can't install 64bit guest OSs. You also need to enable Intel-VT or AMD-V in your BIOS (if it's supported in your BIOS) to run 64bit guest OSs.

Mike ThomasConsultant
Top Expert 2010

You can use this tool from intel (assuming its an intel CPU)

The message given by the 64bit install would suggest that the CPU is indeed 32bit or at best 64bit but with no VT support. it is possible to have any mox of 32 and 64bit in any data store, it will be your CPU that's causing this.

ESXi 4.0 cannot be installed unless and until you have a 64-Bit CPU since its a 64-Bit Hypervisor.
Login to the ESXi 4.0 Host using vSphere Client and post a screen-shot (PNG Format) of
Configuration -> Processors view.
Fetch the CPU info.
If its an Intel CPU, use the below mentioned URL to check the CPU specs


Thanks, the VMWare tool worked a treat. (It is 32-bit =( as I suspected)
As per this URL, ESXi 4.0 cannot be installed on a x86 CPU.
URL : http://tinyurl.com/27568go
May I know how you did it ?


arunraju, yes that's what I thought (about ESXi being 64 bit).. but everything else seems to be pointing to it being 32-bit.

I've attached the screenshot, but it doesn't seem to provide enough information to narrow it down further than a Xeon 3.20 GHz.

VMWare's CPUID bootable CD says:

Supports 64-bit Longmode : Yes
Supports 64-bit VMware   : No
Top Expert 2010

@arunraju: Actually, it can be installed on x86, but not 32bit x86; reference your link:

"VMware ESXi 4.0 will only install and run on servers with 64-bit x86 CPUs."

As far as CPUs are concerned, there are only 3 types with respect to Intel,
x86, x86-64 or x64 and IA-64 (Itanium)
When it states, x86-64, it refers to x64 as well.
If VT is probably not available in your CPU, then you can install ESXi 4.0, but you cannot deploy 64-Bit Virtual Machines within ESXi 4.0 Host.
Your Host must be having the below mentioned CPU since you have Hyper-Threading enabled but VT unavailable.


It looks like "Supports 64-bit Longmode : Yes" means the CPU is 64-bit, but "Supports 64-bit VMware: No" probably refers to the VT mode.

Thanks for the help.
Top Expert 2010

I have DL 380 servers, but the G5 model. I think the G5 was the 1st generation to have Virtualization technology within the BIOS...G4 does not.