Member Avatar for tyberium

OS: Win XP sp2
Dell Dimmension B110

The first symptom was the onboard network connector stopped working. On reboot the blue bios screen appeared. the error number is:
0x000000A5 (0x00010007, 0x00000038, 0x00000000, 0x00000000)

I have already tried removing the battery on the motherboard, and flipping the two pin connector inorder to clear the settings.

Thanks

  • 3 Contributors
  • 3 Replies
  • 375 Views
  • 6 Years Discussion Span
  • Latest Post Latest Post by mirjalali

Dani AI

Generated

This thread illustrates a common, hardware-level cause of STOP 0x000000A5 (ACPI_BIOS_ERROR) on older Windows XP-era machines: a legacy PCI device that interferes with BIOS ACPI enumeration. OP removed a 56.6k PCI modem and recovered, and later replies from and report the same pattern with Wi-Fi and modem cards.

Why it fails: during early boot the BIOS builds ACPI tables and enumerates PCI devices. A card that presents a malformed option ROM or incorrect resource info can make the ACPI tables inconsistent so the kernel halts with 0xA5 before Windows loads. That means the fault is usually firmware/hardware-level rather than a normal Windows driver problem.

  • Strip the system to minimum hardware: keep only CPU, one stick of RAM, the primary boot disk and video. Remove all PCI cards, extra drives and nonessential USB devices, then try to boot. A successful minimal boot points to an offending peripheral.
  • Isolate the culprit by reinserting cards one at a time or testing each card in a different slot or another machine. Note that flaky cards often trigger repeated "Add New Hardware" notices before producing the fatal ACPI error.
  • Update the motherboard firmware using the OEM BIOS for the exact model (use Dell support for a Dimension B110) and follow vendor instructions. If flashing is not possible, try toggling ACPI-related BIOS options (ACPI/APM, Plug and Play OS, legacy USB) one change at a time and retest.
  • Clear CMOS with the motherboard jumper (preferred) or remove the battery for several minutes, then restore defaults.
  • If the card is required but incompatible, replace it with a modern USB or supported PCI alternative.

Flashing BIOS carries risk, so document a known-good configuration first. The recurring theme in this thread points to hardware/firmware incompatibility; removing or replacing the offending card is often the most practical and permanent solution.

Member Avatar for tyberium

Well I figured out what was the matter. There was a 56.6k modem in a PCI slot that should not have been. Once removed the computer works fine.

Member Avatar for sparkyuiop

Thanks for that. I tried updating BIOS, changing RAM, CMOS Reset with no change untill I removed the PCI Wi-Fi card and it booted first time.
Ta!

Member Avatar for mirjalali

Thank you.
I just removed the modem and the system started up normally again.
For your information, I used to get "Add new hardware wizard" windows/balloons for that modem frequently for a few months. Just ignored them though, because I had a good ADSL connection and did not use the 56K modem anymore.
This page saved me a lot!
Thank you so much!!! :)

Edited by mirjalali because: adding more info
Be a part of the DaniWeb community

We're a friendly, industry-focused community of developers, IT pros, digital marketers, and technology enthusiasts meeting, networking, learning, and sharing knowledge.