Bottom Line: Separate “Download Is Incomplete” From “USB Will Not Boot”
The thread contains two different failures. First, the browser could not finish downloading the 1.78 GB installer. An alternate ISO downloaded successfully. Later, both the experimental ISO and beta IMG reached the HP Z440 firmware but failed to start the installer. Those require different checks; changing the download mirror cannot fix a BIOS boot-mode problem.
Use the Current Official IMG Path, Not the 2025 Experimental Slim ISO
Current ZimaOS installation instructions say to download the latest zimaos_XXXXX_installer.img from the official GitHub release, flash it with Balena Etcher, boot the target in UEFI mode and disable Secure Boot. The 2025 OneDrive-hosted slim ISO was an experimental workaround for one download case, not the modern installation source.
The ZimaOS installer steps is the current procedure. The ZimaOS release assets is the release source.
Verify the Download Before Flashing
If a browser repeatedly stops at the same point, try another network/browser or download directly from the official release host. Compare file size and any published checksum before writing the USB. A partially downloaded IMG can still have a plausible filename but will not produce a valid installer.
Do not diagnose USB boot until the downloaded file itself is complete.
Flash the IMG as an Image, Not as a Normal File Copy
Use Balena Etcher or another raw-image writer and select the downloaded IMG as the source. After writing, let the tool verify the flash. The target USB will be erased. Etcher's Balena Etcher is the tool named by current ZimaOS instructions.
On an HP Z440, Check UEFI and Secure Boot Before Anything Else
ZimaOS is designed for generic x86-64 with UEFI. If firmware is set to Legacy-only boot, or Secure Boot blocks the unsigned installer path, the system may never reach the ZimaOS installer. Enable UEFI, disable Secure Boot, and explicitly choose the UEFI entry for the flashed USB.
PXE Boot Usually Means the Firmware Skipped the Intended USB
The Intel Boot Agent screen shows the workstation moving on to network boot. That is useful evidence: the firmware did not successfully execute the intended local USB entry. Recheck boot order, UEFI USB detection, flash integrity and the specific USB port rather than waiting at PXE.
Use a Minimal Boot Configuration
Disconnect unnecessary data disks, PCIe cards and network boot options while proving the installer. Leave only the target OS disk, USB installer, display and keyboard. This reduces the chance that an old workstation's HBA, GPU option ROM or legacy boot configuration changes the path before ZimaOS starts.
Do Not Install to a Disk With Unverified Data
The ZimaOS installer erases the selected target drive. Identify disks by model and size before confirming. The ZimaOS installation recovery covers the destructive boundary, while the ZimaBoard 2 platform provides a known Zima hardware reference when a legacy workstation remains incompatible.
If the Current Installer Still Hangs
Capture the exact last line on screen, HP Z440 firmware version, UEFI/Legacy setting, Secure Boot state, GPU, storage controller and the current ZimaOS installer version. “It stops at boot menu” is not enough to distinguish firmware compatibility from a kernel/graphics/controller issue. Test one variable at a time.
FAQ
Where should I download ZimaOS now?
Use the current official ZimaOS GitHub release asset linked from the ZimaSpace installation instructions, not the historical slim ISO from the forum.
Does ZimaOS require UEFI?
Current installation instructions specify UEFI boot mode and Secure Boot disabled.
Why does my PC enter PXE after selecting USB?
Firmware may have failed to boot the USB and moved to the next boot option. Recheck the flashed image, UEFI USB entry and boot order.
Can I use an ISO instead of the IMG?
The current official workflow is built around the installer IMG. Do not assume the old experimental ISO is equivalent to the supported path.
Will the installer erase my disk?
Yes, the selected installation target is destructive. Disconnect or clearly identify disks containing important data before installation.
