Techniques for transparently replacing a processor, that receives interrupts in a partitioned computing device, with a replacement processor, are disclosed. In at least some embodiments, methods are discussed for directing the interrupts to an unchangeable identifier mapped to the processor's identifier and replacing the processor with the replacement processor. An intermediary, such as an I/O APIC, is used for storing the unchangeable identifier. The mapping may use logical mode delivery, physical mode delivery, or interrupt mapping.