RAID 5 configuration: Using five of the available drives in a RAID 5 configuration meets the requirements for:
Storage capacity: Four 600GB drives (2, 5, and 6) provide a total usable capacity of 2.4TB (4 *
600 * 0.8), exceeding the minimum requirement of 2TB. RAID 5 introduces parity data for fault tolerance, sacrificing some usable space (one drive's worth).
Performance: The combination of multiple drives in a RAID 5 array improves read performance compared to a single drive setup.
Fault tolerance: Even with a single drive failure (any of the five drives used in the RAID 5), the remaining drives can reconstruct the lost data, allowing the server to continue operating.

Explanation
The loud noises from the servers are most likely caused by failing hard disk drives, which can produce clicking or grinding sounds. Replacing the drives with new ones can prevent data loss and downtime.
Replacing the drives can be done without shutting down the server if they are hot-swappable, which means they can be removed and inserted while the server is running. References: CompTIA Server+ Certification Exam Objectives, Domain 3.0: Storage, Objective 3.1: Given a scenario, install, deploy, configure and update physical storage devices.

If a server has three hard drives configured in a RAID 5 array, it means that the data is striped across all three drives with parity information. RAID 5 can tolerate one drive failure without losing data, but not two or more. If there are multiple failed hard drives, the RAID 5 array will become corrupted and the OS will not load. The other options are not likely to cause the issue, as the server passes POST, the CPU and RAM are seated correctly, the BIOS settings are correct, and the OS loads from a bootable USB drive. RAID 5 does not require four drives, it can work with three or more. Reference: https://www.technewstoday.com/what-is-a-raid-5/

A synthetic full backup is a type of backup that combines a full backup with one or more incremental backups to create a new full backup without accessing the source data. This type of backup is suitable for database servers, as it reduces the backup window, minimizes the impact on the server performance, and provides faster recovery time. Verified Reference: [Synthetic Full Backup]

Explanation
The HCL stands for Hardware Compatibility List and it is a list of hardware devices that are tested and certified to work with a specific operating system. If a network card is not on the HCL for the OS, it may not function properly or cause compatibility issues. Therefore, verifying the network card is on the HCL for the OS should be the next step to troubleshoot this issue. References:
https://www.comptia.org/training/resources/exam-objectives/comptia-server-sk0-005-exam-objectives (Objective 4.1)