There is a very rare instance that may happen under Windows 7 if you upgrade your processor from a single to a dual or a dual to a tri or a tri to quad core processor. Under Windows Task manager > Performance tab you may encounter only the previous amount of cores visible even if you have Task Manager > View > CPU history > One Graph per CPU checked off. This graph pane area which should show the equivalent amount of cores per graph is directly tied into the MSConfig > Boot tab > Advanced options > "Number of Processors" setting. You may not show the correct amount of cores in this MSConfig pull-down. Let me give an example: You install Windows 7 with a dual-core processor and have this option checked for "Number of Processors" (in Msconfig > Boot > Advanced options) and the amount set to "2" (for dual core). This setting is not mandatory to be set but some ppl do in order to force Task Manager to show 2 graphs (or 3). One graph for each processor. At a later point in time you upgrade to a Quad-core or Tri-Core processor. The OS will not read this extra core or have anything enabled to physically use this extra core(s) until the following are performed: Uncheck in MSConfig > Boot tab > Advanced Options > "Number of Processors" and exit MSConfig d/l and install an applet called EasyBCD 1.7.2 (or later, Google: EasyBCD) which supports many features of Windows 7. Go into Advanced Options in EasyBCD and select "Limit Widows to '0' CPUs (Leave 0 to reset)". Click "Apply Settings" and exit EasyBCD. NOTE: This will force the OS to reset the count to default for the amount of Cores you now have. There is possibly a boot setting that can be added that I may not be aware of to do this same function but this little applet works and does the same thing. Don't muck around with any other setting in this utility if you don't know what you are doing it may leave your computer unbootable and a complete reinstall or long repair may need to be performed. Just make sure this one setting is set to "0" Completely shutdown the OS (not reboot or restart or logout). Correctly Shutdown you computer so the it powers down. upon restart into the OS the Task Manager > Performance tab should now show the correct amount of per core graphs if you have the "One Graph per CPU" option selected. Yay your back in business =) Notes: Some of these discrepancies will appear if your OS is reading the incorrect amount of cores. Device Manager will show the correct amount of Cores for the PC after the new CPU is installed even tho Task Manager still shows the old amount of cores. This is why you need to preform these steps above to fix this disparity and enable the OS to work with the new additional core. CPU-Z (Google: CPUID CPU-Z) will show an incorrect amount of cores until you preform the above steps. SiSoft Sandra (Google: SiSoft Sandra) will show the correct amount of Cores for the PC after the new CPU is installed even tho Task Manager still shows the old amount of cores. This is why you need to preform these steps above to fix this disparity and enable the OS to work with the new additional core. Reinstalling Windows 7 with the "Upgrade" (not Custom Option) will not fix this issue until the above steps are performed. The reinstall should clear the "Number of Processors" setting in MSConfig but it doesn't! Hence the need to run the above steps and avoid a reinstall which takes greatly more time and still does not fix this issue. In a dual boot (XP/Win7) PC, the XP Task Manager will show the correct amount of Cores in Task Manager > Performance tab even tho the same place under Windows 7 will not! Hence the need to perform the above steps. This is a rare issue, but if you are upgrading CPUs in the future these are a very important steps to enable your Win7 OS to take advantage of this extra core you are buying. Even tho in places like Device Manager it will show the correct amount of cores the MSConfig setting will override the Device Manager only allow you to work with a lessor amount of cores thereby limiting your CPUs true potential preserving your good investment. Good Luck! I hope someone who encounters this issue finds their way here after a CPU upgrade or they may rip their hair out and I can tell you from experience I was making the Level 3 tech support at Microsoft rip their hair out when I found this issue lol I was getting an Experience Index value for Processor of 6.3 when this core was disabled and not showing up in Task Manager > Performance tab. Once the above steps were performed my Performance Index jumped to 6.9! My old Dual-Core CPU was an Experience Index of 6.1 to show you the difference a 3rd core can add to your system. In the future, once I start gently Overclocking my new Triple-core processor (once I get a better CPU cooler) It should exceed 7.2-7.4 or greater Experience Index. =) TCsenter wrote also: Some recommendations (make sure you are running as Administrator): Run MSConfig -> Change to Boot tab -> Advanced Options -> "Number of Processors", make sure there is no check mark. Delete processor entries listed in Device Manager, then reboot and allow Windows to redetect/reinstall them. In BIOS, check for an option named Max CPU ID Value or CPU ID Max Val and make sure its set to disabled . This option is only provided for OS prior to Windows 2000. Save and Exit BIOS. Check for a BIOS update for your system or motherboard. Confirm the CPU model is supported by the motherboard

You got my quad core running great with that bit of advice. Thank you sir!

OMG thank you! You sir are a scholar and a gentleman. I went from 2 to 6 cores and this was the ticket. Everything seems to work now!

I'd wanted to post up here and let everyone know this also works when you reduce the number of cores in Windows 7! Now most people are wondering why I would want to do that. I will explain: I built a Win7Pro SP1 x64 virtual machine on VMware ESXi 4. I assigned 2 vCPU’s to it from the beginning. It worked fine with this config for months. As a part of a larger effort on other virtual workstations and servers, we are reducing the number of cores on VM’s that don’t need the extra horsepower. (Interesting blog post about the subject if anyone is interested: http://virtualblocks.wordpress.com/2010/06/22/cpu-ready-over-built-vm-or-over-utilized-host/ ) Anyway, our Server 2008 systems don’t skip a beat when reducing the number of cores. However, my Windows 7 VM would freeze after windows started to load. I had to increase the vCPU back to 2 in order for it boot up fully. Then I was able to use the procedure with msconfig and EasyBCD and drop it back to 1 vCPU. All is well and everything is what it should be (device and task manager, CPU-Z, etc.) Appreciate the thorough write-up Passionfly!

Hello and thanks so much for this post! I've managed to fix my computer using EasyBCD 2.0. The problem was that, somehow, it recognized and used only one core, resulting in slow performance in heavy application likes video editing. With this, it fixed everything. My machine is a Macbook Pro 13 (Early 2011) Thanks!

That is TOTAL C R A P, Windows home premium is fully capable of supporting multi-core processors natively in either 32 or 64 bit install. Whomever told you this you need to call them back and tell them to go to school cause they are full of C R A P. I will direct you to the Windows 7 System Requirements . Perhaps it's you that needs to "go to school because you are full of C R A P"? The poster you responded to, specificaly stated that he had two [physical] dual-core CPUs. Quote: PCs with multi-core processors: Windows 7 was designed to work with today's multi-core processors. All 32-bit versions of Windows 7 can support up to 32 processor cores, while 64‑bit versions can support up to 256 processor cores. PCs with multiple processors (CPUs): Commercial servers, workstations, and other high-end PCs may have more than one physical processor. Windows 7 Professional, Enterprise, and Ultimate allow for two physical processors, providing the best performance on these computers. Windows 7 Starter, Home Basic, and Home Premium will recognize only one physical processor. 2 dual cores would still be considered a quad not "2 duals" but this is just a semantic and no sense beating a dead horse, so to speak. No, they're completely different. If you have an 8 cylinder car, is that the same as a car with 2 4 cylinder engines? Heck no. This is much the same matter.

HOWTO: Get Windows 7 to detect your new multi-core processor

Anonymous

There is a very rare instance that may happen under Windows 7 if you upgrade

your processor from a single to a dual or a dual to a tri or a tri to quad core processor. Under Windows Task manager > Performance tab you may encounter only the previous amount of cores visible even if you have Task Manager > View > CPU history > One Graph per CPU checked off.

This graph pane area which should show the equivalent amount of cores per graph is directly tied into the MSConfig > Boot tab > Advanced options > "Number of Processors" setting. You may not show the correct amount of cores in this MSConfig pull-down.

Let me give an example:

You install Windows 7 with a dual-core processor and have this option checked for "Number of Processors" (in Msconfig > Boot > Advanced options) and the amount set to "2" (for dual core). This setting is not mandatory to be set but some ppl do in order to force Task Manager to show 2 graphs (or 3). One graph for each processor. At a later point in time you upgrade to a Quad-core or Tri-Core processor. The OS will not read this extra core or have anything enabled to physically use this extra core(s) until the following are performed:

Uncheck in MSConfig > Boot tab > Advanced Options > "Number of Processors" and exit MSConfig
d/l and install an applet called EasyBCD 1.7.2 (or later, Google: EasyBCD) which supports many features of Windows 7.
Go into Advanced Options in EasyBCD and select "Limit Widows to '0' CPUs (Leave 0 to reset)". Click "Apply Settings" and exit EasyBCD.

NOTE: This will force the OS to reset the count to default for the amount of Cores you now have. There is possibly a boot setting that can be added that I may not be aware of to do this same function but this little applet works and does the same thing. Don't muck around with any other setting in this utility if you don't know what you are doing it may leave your computer unbootable and a complete reinstall or long repair may need to be performed. Just make sure this one setting is set to "0"

Completely shutdown the OS (not reboot or restart or logout). Correctly Shutdown you computer so the it powers down.
upon restart into the OS the Task Manager > Performance tab should now show the correct amount of per core graphs if you have the "One Graph per CPU" option selected. Yay your back in business =)

Notes: Some of these discrepancies will appear if your OS is reading the incorrect amount of cores.

Device Manager will show the correct amount of Cores for the PC after the new CPU is installed even tho Task Manager still shows the old amount of cores. This is why you need to preform these steps above to fix this disparity and enable the OS to work with the new additional core.
CPU-Z (Google: CPUID CPU-Z) will show an incorrect amount of cores until you preform the above steps.
SiSoft Sandra (Google: SiSoft Sandra) will show the correct amount of Cores for the PC after the new CPU is installed even tho Task Manager still shows the old amount of cores. This is why you need to preform these steps above to fix this disparity and enable the OS to work with the new additional core.
Reinstalling Windows 7 with the "Upgrade" (not Custom Option) will not fix this issue until the above steps are performed. The reinstall should clear the "Number of Processors" setting in MSConfig but it doesn't! Hence the need to run the above steps and avoid a reinstall which takes greatly more time and still does not fix this issue.
In a dual boot (XP/Win7) PC, the XP Task Manager will show the correct amount of Cores in Task Manager > Performance tab even tho the same place under Windows 7 will not! Hence the need to perform the above steps.

This is a rare issue, but if you are upgrading CPUs in the future these are a very important steps to enable your Win7 OS to take advantage of this extra core you are buying. Even tho in places like Device Manager it will show the correct amount of cores the MSConfig setting will override the Device Manager only allow you to work with a lessor amount of cores thereby limiting your CPUs true potential preserving your good investment.

Good Luck! I hope someone who encounters this issue finds their way here after a CPU upgrade or they may rip their hair out and I can tell you from experience I was making the Level 3 tech support at Microsoft rip their hair out when I found this issue lol

I was getting an Experience Index value for Processor of 6.3 when this core was disabled and not showing up in Task Manager > Performance tab. Once the above steps were performed my Performance Index jumped to 6.9! My old Dual-Core CPU was an Experience Index of 6.1 to show you the difference a 3rd core can add to your system. In the future, once I start gently Overclocking my new Triple-core processor (once I get a better CPU cooler) It should exceed 7.2-7.4 or greater Experience Index. =)

TCsenter wrote also:

Some recommendations (make sure you are running as Administrator):

Run MSConfig -> Change to Boot tab -> Advanced Options -> "Number of Processors", make sure there is no check mark.
Delete processor entries listed in Device Manager, then reboot and allow Windows to redetect/reinstall them.
In BIOS, check for an option named Max CPU ID Value or CPU ID Max Val and make sure its set to disabled . This option is only provided for OS prior to Windows 2000. Save and Exit BIOS.
Check for a BIOS update for your system or motherboard.
Confirm the CPU model is supported by the motherboard

Locked Question. This question was migrated from the Microsoft Support Community. You can vote on whether it's helpful, but you can't add comments or replies or follow the question.

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60 answers

Anonymous

2010-06-06T17:35:51+00:00

You got my quad core running great with that bit of advice. Thank you sir!
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Anonymous

2010-11-13T00:58:24+00:00

OMG thank you! You sir are a scholar and a gentleman. I went from 2 to 6 cores and this was the ticket. Everything seems to work now!
Was this answer helpful?

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Anonymous

2011-05-17T19:32:11+00:00

I'd wanted to post up here and let everyone know this also works when you reduce the number of cores in Windows 7!

Now most people are wondering why I would want to do that. I will explain:

I built a Win7Pro SP1 x64 virtual machine on VMware ESXi 4. I assigned 2 vCPU’s to it from the beginning. It worked fine with this config for months. As a part of a larger effort on other virtual workstations and servers, we are reducing the number of cores on VM’s that don’t need the extra horsepower. (Interesting blog post about the subject if anyone is interested: http://virtualblocks.wordpress.com/2010/06/22/cpu-ready-over-built-vm-or-over-utilized-host/ )

Anyway, our Server 2008 systems don’t skip a beat when reducing the number of cores. However, my Windows 7 VM would freeze after windows started to load. I had to increase the vCPU back to 2 in order for it boot up fully. Then I was able to use the procedure with msconfig and EasyBCD and drop it back to 1 vCPU. All is well and everything is what it should be (device and task manager, CPU-Z, etc.)

Appreciate the thorough write-up Passionfly!
Was this answer helpful?

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Anonymous

2011-05-18T17:13:39+00:00

Hello and thanks so much for this post!

I've managed to fix my computer using EasyBCD 2.0. The problem was that, somehow, it recognized and used only one core, resulting in slow performance in heavy application likes video editing. With this, it fixed everything.

My machine is a Macbook Pro 13 (Early 2011)

Thanks!
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Anonymous

2011-11-23T00:37:13+00:00

That is TOTAL C R A P, Windows home premium is fully capable of supporting multi-core processors natively in either 32 or 64 bit install. Whomever told you this you need to call them back and tell them to go to school cause they are full of C R A P.

I will direct you to the Windows 7 System Requirements. Perhaps it's you that needs to "go to school because you are full of C R A P"? The poster you responded to, specificaly stated that he had two [physical] dual-core CPUs.

Quote:

PCs with multi-core processors:

Windows 7 was designed to work with today's multi-core processors. All 32-bit versions of Windows 7 can support up to 32 processor cores, while 64‑bit versions can support up to 256 processor cores.

PCs with multiple processors (CPUs):

Commercial servers, workstations, and other high-end PCs may have more than one physical processor. Windows 7 Professional, Enterprise, and Ultimate allow for two physical processors, providing the best performance on these computers. Windows 7 Starter, Home Basic, and Home Premium will recognize only one physical processor.

2 dual cores would still be considered a quad not "2 duals" but this is just a semantic and no sense beating a dead horse, so to speak.

No, they're completely different. If you have an 8 cylinder car, is that the same as a car with 2 4 cylinder engines? Heck no. This is much the same matter.
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2 people found this answer helpful.

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