BIOS/CMOS and fixed disk errors: Identify the most plausible cause A PC reports a “fixed disk error” during startup. Which of the following is the most likely underlying cause to investigate first?

Introduction / Context:
During POST, the BIOS queries disk parameters stored in CMOS (or autodetected). If these parameters do not match the actual drive, the BIOS may fail to recognize or initialize the disk, yielding “fixed disk” errors.

Given Data / Assumptions:

• Error appears before the operating system loads.
• Legacy systems may rely on manually entered cylinders/heads/sectors, while newer BIOSes use auto-detect.
• Battery or user changes could alter CMOS entries.

Concept / Approach:

First validate BIOS disk detection: ensure correct drive mode (Legacy/IDE/AHCI), boot order, and geometry parameters. If CMOS battery is weak, settings can reset and cause detection failures.

Step-by-Step Solution:

Verification / Alternative check:

After correcting BIOS/CMOS settings, the system should pass POST and enumerate the disk. If the error persists, test the drive with vendor tools or swap cables/ports to rule out hardware faults.

Why Other Options Are Wrong:

• Bad RAM: could cause general POST failures but not a specific “fixed disk” message.
• Slow processor: unrelated to disk detection and would not generate this error.
• No-CD installed: optical drives are irrelevant to fixed disk initialization.
• None of the above: incorrect because CMOS settings commonly cause this error.

Common Pitfalls:

Overlooking SATA mode mismatches (e.g., OS installed under AHCI but BIOS reset to IDE), and ignoring failing CMOS batteries that intermittently lose settings.

Final Answer:

Incorrect CMOS settings