If you apply 3.3V before 0.9V, internal ESD diodes will forward bias, sending current into the core illegally. The datasheet is explicit about a maximum ramp time of 100ms. Violating this is the #1 cause of "dead AST2500" on custom carrier boards.
Configured via strapping pins (sampled at reset): Aspeed Ast2500 Datasheet
A critical feature of any advanced BMC is the ability to redirect the host's display over the network (KVM-over-IP). The AST2500 features a high-performance integrated graphics engine. If you apply 3