hey y'all - was looking for some insight with an odd issue i was facing:

Issue:
My new ASUS mobo throws the "GPT Header Corruption has been detected..." error at post but only when two of my HDDs are plugged into the StarTech ASM1166 card.

Workaround atm: Pressing F1 to get past the error and into BIOS, selecting the Unraid USB to launch as normal. Further workaround would be to disable waiting at POST errors via BIOS, but haven't done that until I find out more.

System:

• Unraid 7.3.1

• ASUS Prime B760M-AYW WiFi D4 II, BIOS 1837, i5-14400

• StarTech 6-Port SATA III 6Gbps PCIe Card, Non-RAID (6P6G-PCIE-SATA-CARD)

  • flashed to firmware 211108-0000-00 (the stock firmware wasn't detecting on my mobo until I flashed / updated)

• 4 onboard SATA ports that are occupied by 3x 12TB HDDs + 1x 4TB HDD

• ASM1166 currently holds 2x 4TB HDDs + 1x Cache SSD

• BIOS: CSM disabled, Secure Boot set to "Other OS", Recovery Policy left to default (Local User Control)

What else I've checked:

• sgdisk -v is clean on every drive

• Long SMART tests have passed on the drives plugged into the StarTech card

• Warning appears with the Unraid USB removed as well

Additional notes:

• StarTech card plugged in with 0 drives plugged in does not prompt the error, and when the SSD Cache drive is plugged in on it's own, it does not cause any issues either

• The same two drives that are causing this error DO NOT prompt the error to appear when plugged into the native sata ports on the motherboard (leading me to believe the drives are not the issue)

• 12TB drives are brand new and passed their addition to parity with 0 issues, 4TB drives are ~3,000 hours in

• SSD is MBR (doesn't trigger the error), both HDDs are GPT and do trigger the error via the card

Questions / Insight I was looking for:

• Is there a known cause for why the drives would only throw this error when plugged into the ASM1166?

• Is this a cosmetic error / is it safe to continue using / storing files on the drives knowing this error appears at POST?

Diagnostic output attached as well, and thank you for any help insight y'all

There's a LSI HBA I can purchase if needed, but wasn't sure if it's worth swapping over from the ASM1166's lower power usage / smaller profile.

diagnostics-20261004-1619.zip

Your diagnostics look fine from the Unraid side. Through the ASM1166, Linux sees both 4TB disks at full size with valid GPT partitions, and the layout is the same as the 4TB disk on the onboard ports. There are no disk or controller errors in the logs, and your clean sgdisk -v matches that. The partitions aren't corrupt.

During POST, the board doesn't read those disks with its own driver. It reads them through the ASM1166's UEFI firmware (option ROM). My best guess is that this option ROM has a problem with disks larger than 2TB. The backup GPT header is stored at the end of the disk, and on a 4TB disk that's past the 2TB point. If the controller firmware reports the wrong size or can't address that far, the BIOS reads the wrong sectors and decides the header is corrupt. That would also explain why the SSD doesn't trigger it: it uses MBR, so the BIOS doesn't check for a GPT on it.

If you want to confirm it, temporarily connect one of the 12TB disks to the card. It should also trigger the warning. A GPT disk smaller than 2TB shouldn't.

Is it safe? For normal use, yes. Unraid doesn't use the card's option ROM, so it's only the BIOS that sees the problem. The one thing to avoid is letting the BIOS "recover" or repair the GPT. If it's reading the disk wrong, a repair could write to the wrong place. Leave the recovery policy at "Local User Control", never accept a repair prompt, and don't set it to automatic.

Options:

- Keep pressing F1, or disable "wait for F1 if error" in the BIOS. Either is fine as long as the BIOS never repairs anything.

- If your BIOS has a setting to disable the option ROM for that PCIe slot, try it. Unraid boots from the USB, so it doesn't need the card's option ROM.

- Use the onboard ports for the large GPT disks and the card for the SSD or smaller disks.

I wouldn't buy an LSI HBA just for this. The card is working correctly in Unraid. The warning only comes from the BIOS.