A ZimaBlade that randomly changes boot order is not normal ZimaOS behavior. In this thread IceWhale said engineering suspected an insufficient CMOS battery and identified the ZimaBlade battery as CR927. Another user found that disabling every non-system boot option reduced the symptom on their unit.
The thread never confirmed whether replacing the battery fixed the original author’s machine, so the battery remains an engineering-supported diagnosis rather than a verified closure for that exact user.
What the BIOS Was Doing
The system had NVMe and SATA storage attached through PCIe, and the external WD Blue drive sometimes moved to the top of the boot list. That forced the user to attach a monitor and keyboard and manually restore the boot order.
IceWhale Suspected the CMOS Battery
An IceWhale reply said engineering believed insufficient CMOS battery power could cause the boot-order state to reset and recommended trying a CR927 replacement.
A separate 2026 community thread later reported a successful fix after replacing a ZimaBlade CR927 battery, which makes the diagnosis more plausible but still not universal.
Reduce the Number of Bootable Alternatives
One user reported success by disabling all boot options except the intended OS device. This is a reasonable mitigation when the BIOS exposes that control, but it does not explain why settings are changing in the first place.
After changing boot options, cold-power-cycle the device several times and confirm the order remains stable before returning it to headless operation. The current ZimaBlade setup guide is the better baseline for current hardware behavior than an old forum-only boot recipe.
Do Not Confuse Boot Order With ZimaOS Data Migration
The source author wondered whether migrating some ZimaOS data to NVMe was responsible. Moving app/data storage should not normally make a data disk the preferred firmware boot device unless that disk also contains a bootable entry or the firmware state changes.
The ZimaOS boot checklist is the safer next step if the intended boot device itself disappears.
Bottom Line
The strongest evidence in the thread is the firmware layer: boot priority changed before ZimaOS loaded. Check the CR927 battery, disable unnecessary boot candidates, save BIOS settings and test repeated cold boots. Reinstalling ZimaOS will not repair a BIOS that forgets its boot order.
