Why are there only two cores in Windows XP?

I'm running Windows XP 32-bit on an Intel Q9650 quad-core CPU.

In Device Manager, I see four cores. It's OK. However in Task Manager, I can only see two cores. Are only two cores used? If so, why are there are four cores in Device Manager?

I'm confused. Does anyone know this problem? Is it related to 32-bit Windows? Perhaps I need to install some patches?

More information: I run Windows XP Embedded in KVM. It's convenience for me to do some simple tests. Are there any problems with XPE in virtualization environment? Or are there any differences between XPE and XP?

Here are the snapshots:

Device manager

Task Manager

flypen

Posted 2011-05-30T10:08:13.220

Reputation: 267

1Are you looking at the "CPU usage" chart? That's not connected to the amount of cores you have. Under "CPU history", is "one graph per CPU" selected? – Rob Moir – 2011-05-30T10:43:06.440

could you post a task manager snapshot please? Furthermore, if you right-click on a running process and select "Set affinity..." from the context menu - what CPUs are you offered to select? – None – 2011-05-30T11:01:21.183

I have attached the snapshots. – flypen – 2011-05-31T07:14:31.810

2it might have been helpful to mention the virtualisation originally. Not being familiar with that virtualisation software, I would wonder if it presents each core to guests as a separate CPU. – Rob Moir – 2011-05-31T07:43:16.423

Robert Moir's comment is just the answer. Thanks a lot! – flypen – 2011-05-31T09:49:23.697

Answers

Use MSconfig to check # of processors allowed, be sure all the boxes are Unchecked. Hit OK, OK if you make changes.

Msconfig> BOOT.INI tab > Advanced Options

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Moab

Posted 2011-05-30T10:08:13.220

Reputation: 54 203

Robert Moir's comment is just the answer. Thanks a lot!

it might have been helpful to mention the virtualisation originally. Not being familiar with that virtualisation software, I would wonder if it presents each core to guests as a separate CPU. – Robert Moir 2 hours ago

flypen

Posted 2011-05-30T10:08:13.220

Reputation: 267

-3

Based on this KB article direct from Microsoft, the 32-bit version of Windows XP only supports a maximum of 2 processors (cores).

user48838

Posted 2011-05-30T10:08:13.220

Reputation:

3processors are not the same as cores. XP is quite happy to support quad core processors. – Rob Moir – 2011-05-30T11:17:03.167