Z420 CPU upgrade - 8c processor only showing 2c 4t

[SeanM88]

I recently acquired a Z420. Came with Nvidia 1650 Super, Xeon E5-1603 installed. and Windows 11.

I was looking to upgrade the CPU to a more powerful one. Upgraded bios to the latest  2019 (J61 3.96) one available on HP site. Checked boot block date on bios - 03/06/2013. Based on research on this HP community posts - my system should support v2 processors. 

Installed a E5-2667 v2 8C 16T processor. Bios show the correct processor. However, in windows 11 - task manager only show and runs 2C 4T, shows no virtualization support. It is the same on HWID where only two cores show being used. Device manager, HWID shows correct CPU E5-2667v2 Ivy bridge). Ran geekbench, same result - 1 Processor, 2 Cores, 4 Threads.

[edited]

So apparently, windows is not using 8 cores or 16 threads.   

Just to test, I installed another CPU I had - E5-2650L v2, which has 10C 20T and lower TDP - the result is the same. Only able to get 2C 4T.

I tried to find any settings I can toggle in bios that allow 8 cores but did not find any. 

Is there something I am missing? How do I get z420 to run full 8C 16T performance? 

[SDH]

I took a look at the most recent Z420 QuickSpecs document I could find and don't see either of those two processors you mention listed as HP certified for use in that workstation. Maybe you're asking the box to do something HP never engineered into it despite yours being a Z420 v2? Think about getting a processor that is officially supported and trying  that.

For example, a E5-1680 v2, single sSpec code of SR1MJ, is going for just 70.00 now on eBay (vs $1723.00 USD when new from Intel).

You don't need E5-2XXX dual QPI links in a Z420... it only runs 1 processor.

I have seen corrupted BIOS CMOS settings hold back a processor just once in the past so also consider first doing a full CMOS clear the long way and start fresh using the factory default BIOS settings. There are some BIOS and Control Panel/Power Options app settings to optimize speed over energy costs too.

I'm running W11 also on our ZX20 boxes via my "hybrid" W10->W11 upgrade method but maybe try W10Pro64 instead for this project. Also note that in W11 when using Windows Update there is an "Advanced options/ Additional options/ Optional updates" pathway lower down in the open window that can include a bunch of optional updates that you won't get if you don't know to go there and enable them. For the ZX40 family at least there is a big bunch of processor enabler optional updates available. Look there also for the ZX20 family if you're using W11.

[DGroves]

many people overlook or forget the fact that the lower spec versions of windows 10/11 (such as home) have built-in limits in regards to multiple cpu or multi core support (along with other limitations)

and earlier MS OS's  such as windows 7/8 only supported up to two processor cores max and non pro releases just a single core/cpu

Windows 8 Pro supports a maximum of 2 physical CPUs and the standard version of Windows 8 just one

1. Press Windows* key + R.
2. Type command: msconfig.
3. In System Configuration Utility, click Boot tab.
4. Click Advanced Options.
5. Uncheck the box Number of Processors.
6. Restart the computer.

you will need to install windows 7 professional (hp oem ver) 64 bit, and then do a upgrade to windows 10 pro x64 in order to ger a free digital win 10 license

PM me for details on where/how to get a HP win 7 Oem disk, and note this disk will only install/activate on HP systems

[SeanM88]

It turns out it is Windows 11. I don't know if it is the windows setting itself or how W11 was installed on this system (tpms bypass etc.) - it was only running 1 core 2 threads. Settings in MSConfig were not available / not changeable. 

Wiped W11, and installed Windows 10 -  all good. All 8 cores, 16 threads are being used. My first clue was during CPU benchmarking/stress testing tool in UBCD, the system was using 16 CPU. It was also the case on a live boot of Linux mint.  

Anyway, Windows 10 seem to work fine regarding this matter. Performance is not similar to other ones I can see in geekbench browser, but it could be a combination of ram/SSD etc. 

[DGroves]

sometimes during a cpu change, the MS OS fails to register the  new cpu in the cpu descriptor string

keeping the old one instead of updating it

this can be resolved by various methods,  depending on the OS revision,  the steps below should work on most systems

1. Press Windows + R.
   • This will open the Run menu.
2. Type in MSConfig.
3. Go to the Boot tab.
4. Select Advanced Options.
5. Look at where it says Number of processors.
6. If the checkbox is enabled, uncheck it.
   • Your system should now use all of its processors whenever given the chance.