What kind of components in a computer power supply can explode loudly?
Lead batteries, used in a UPS, can explode violently due to hydrogen gas buildup.
Mechanical damage will be evident, since the battery encapsulation will have failed.
I put my money on this, if it can be heard from rooms away.

Diodes and traces can explode without much mechanical damage or residue. Yet they can sound like a small lightning bolt depending on the fault current capacity or in other words, the energy let through by the protection circuitry.

Electrolytic capacitors can rocket off a board, but they tend to poof a lot of smoke and crud. However, in a server the airflow might dissipate this quickly.

Tantalum and ceramic capacitors go up in flames. Not much bang.

Resistors will often show burning of the PCB first. Otherwise they've exploded on a surge condition, and they will be scattered around the enclosure, similar to diodes.

Fuses will only explode when selectivity or breaking capacity is improperly allocated.