🧩 Problem#

I attempted to install ESXi 8 on my Dell OptiPlex homelab machine, but during boot, I encountered a Pink Screen of Death (PSOD) with errors like:

  • Fatal CPU mismatch on feature
  • HW feature incompatibility detected

This prevented ESXi from installing or booting successfully. !Image Description

🛠️ Root Cause#

The issue is caused by modern Intel CPUs (12th Gen and newer) using a hybrid architecture with:

  • Performance cores (P-cores)
  • Efficiency cores (E-cores)

ESXi expects uniform CPU cores, so it crashes when it detects different core types.

🛠️ Solution Overview#

I applied a workaround by disabling ESXi’s CPU uniformity check using a kernel boot parameter:

cpuUniformityHardCheckPanic=FALSE

This allowed ESXi to install and run successfully. Thanks and Credits due to : https://williamlam.com/2023/01/video-of-esxi-install-workaround-for-fatal-cpu-mismatch-on-feature-for-intel-12th-gen-cpus-and-newer.html

🔧 Environment#

  • Dell OptiPlex (Intel CPU with hybrid cores)
  • ESXi 8 ISO
  • Bootable USB installer

🚀 Step 1: Boot ESXi Installer#

  • Created bootable USB with ESXi 8
  • Booted the OptiPlex from USB

⚠️ Step 2: Fix PSOD During Installation#

When the ESXi installer starts:

  1. Press:
SHIFT + O
  1. Append the following to the boot line:
cpuUniformityHardCheckPanic=FALSE
  1. Press Enter to continue boot

This bypasses the CPU compatibility check. !Image Description

💿 Step 3: Install ESXi Normally#

  • Follow the standard ESXi installation wizard
  • Select disk
  • Set root password

⚠️ Important: Do NOT reboot immediately after installation

🛠️ Step 4: Make Fix Persistent (Before Reboot)#

Press:

ALT + F1

Login:

Username: root
Password: (blank)

Edit boot config:

vi /vmfs/volumes/BOOTBANK1/boot.cfg

Update the kernel line:

kernelopt=weaselInstalled autoPartition=FALSE cpuUniformityHardCheckPanic=FALSE

Save and exit:

ESC → :wq

!Image Description

🔄 Step 5: Reboot System#

Press:

ALT + F2

Then reboot the system.

⚙️ Step 6: Make Setting Permanent (After Install)#

Enable ESXi shell:

  • Press F2
  • Go to Troubleshooting Options
  • Enable ESXi Shell

Then:

ALT + F1

Run:

esxcli system settings kernel set -s cpuUniformityHardCheckPanic -v FALSE

!Image Description

!Image Description !Image Description

(Optional) Step 7: Prevent Future PSOD (Newer CPUs)#

For newer CPUs (e.g., 13th Gen), also run:

esxcli system settings kernel set -s ignoreMsrFaults -v TRUE

📊 Result#

  • ESXi 8 installed successfully
  • No more PSOD during boot
  • Stable homelab hypervisor running

⚠️ Challenges Faced#

  • Repeated PSOD during installation
  • Not knowing boot parameter initially
  • Kernel setting not persisting after reboot

🧠 What I Learned#

  • Modern CPUs use hybrid core architecture
  • ESXi has strict CPU uniformity checks
  • Kernel parameters can override hardware limitations

🚀 Future Improvements#

  • Disable E-cores in BIOS for cleaner setup
  • Upgrade to supported hardware
  • Explore vCenter integration

🔥 Key Takeaway#

If you see a PSOD during ESXi install on newer Intel CPUs, it is most likely due to hybrid cores—and can be fixed using:

cpuUniformityHardCheckPanic=FALSE