Core 2 duo desktop, but taskman and perfmon only report one cpu

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I have a core 2 duo desktop, but in taskman i can only see one panel in the performance tab, where i’m certain there should be two. Also, in perfmon, under Processor -> % Processor Time, there is only “_Total” and “0” instance.

Am i missing some dual code driver or something?

Here’s my results from Intels PID, which says that i have a core 2 duo:

Intel(R) Processor Identification Utility
Version: 4.10.20090310
Time Stamp: 2009/08/17 02:06:26
Number of processors in system: 1
Current processor: #1
Active cores per processor: 2
Disabled cores per processor: 0
Processor Name: Intel(R) Core(TM)2 Duo CPU E6300 @ 1.86GHz
Type: 0
Family: 6
Model: F
Stepping: 2
Revision: 51
Maximum CPUID Level: A
L1 Instruction Cache: 2 x 32 KB
L1 Data Cache: 2 x 32 KB
L2 Cache: 2 MB
Packaging: LGA775
Enhanced Intel SpeedStep(R) Technology: Yes
MMX(TM): Yes
Intel(R) SSE: Yes
Intel(R) SSE2: Yes
Intel(R) SSE3: Yes
Intel(R) SSE4: No
Enhanced Halt State: Yes
Execute Disable Bit: Yes
Intel(R) Hyper-Threading Technology: No
Intel(R) 64 Architecture: Yes
Intel(R) Virtualization Technology: Yes
Expected Processor Frequency: 1.86 GHz
Reported Processor Frequency: 1.86 GHz
Expected System Bus Frequency: 1066 MHz
Reported System Bus Frequency: 1066 MHz

edit2: Here’s my boot.ini:

[boot loader]
[operating systems]
multi(0)disk(0)rdisk(0)partition(1)WINDOWS="Microsoft Windows XP Professional" /fastdetect

edit3: Under Device manager -> ‘Computer’, i have ‘Advanced Configuration and Power Interface (ACPI) PC’, it doesn’t say anything about multiprocessing.

edit4: This would explain how things got in this state: I originally had a single-core PC. To upgrade, i removed my hard drive and put it into this newer, dual core PC. Seems like the drivers didn’t automatically upgrade.

edit5: In the end, it was the wrong HAL that was causing the problem, i followed the instructions here to solve it:


Could you check which version of the Windows XP hardware abstraction layer your system is using? To do this, run devmgmt.msc, look at what item is displayed as the child of “Computer” in the tree, and add this info to your question: “ACPI Multiprocessor PC”, “ACPI Uniprocessor PC”, “Advanced Configuration and Power Interface (ACPI) PC”, “Standard PC”, etc.

If you’re not using the “ACPI Multiprocessor PC” HAL, then it sounds like either Sysprep (oops, this won’t work) or an in-place upgrade is in order. Here’s a knowledgebase explaining How to perform an in-place upgrade (reinstallation) of Windows XP.

Run this and make sure you didn’t get ripped off(there has been instances of people being sold reboxed/labelled CPUs):

Make sure it is a Intel Core 2 Duo, and not just an Intel Core 2.

Have you overclocked this chip at all?

In the Processes tab, if you right click a process and click “Set Affinity…” are there two check boxes enabled?

In your BIOS see if there is anything fishy with CPU temps, or any other health indicators.

See this if you’re running Vista:

Edit: there may also be options to enable cores in your BIOS

Edit2: In Win XP, right click on “My Computer” -> Properties -> Advanced -> Startup & Recovery;

Click “edit” to edit the Windows Boot.ini file manually. Make sure it doesn’t contain something like /numproc=1 or /ONECPU

Under Control Panel->Administrative Tools->Computer Management->Device Manager->Processors-> You should see two processors listed here. (I have the Core 2 Duo e6400 listed twice)

I saw one post where someone said they had a 4 core processor, and it listed only two cores under Device Manager, so they deleted those two cores here, and let windows reinstall drivers for the new CPU(apperently they had changed CPUs. This however was on Vista.) I would be scared to do this though. I would first try finding updated drivers for my motherboard chipset.

I haven’t a Windows computer to check right now but I remembre that, at least on Windows 2003, there is a préférence somewhère in thé task manager to show graph as if there were only one cpu.

You may also want to look at the bios settings to be sure that thé cpu is correctly recognized and that both Core are enabled.

Also check properties from “My Computer” on the Windows desktop

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