Bug ID 16480679
Issue: The server defaults in BIOS to 64-bit MMIO (Memory Mapped I/O). This allows additional PCIe memory address space to be mapped above the standard 32-bit 4 GB of space for PCIe cards that include option ROMs. However, VMware ESXi is incompatible with MMIO space above the standard 4 GB. This issue can cause some PCIe cards to function improperly with ESXi.
Affected software: VMware ESXi 5.5
Workaround: As a possible workaround, disable 64-bit MMIO through the server's BIOS Setup Utility (under the IO → PCIe Subsystem Settings → PCIe 64-bit Resources Allocation menu). This workaround has limitations. With some combinations of option cards, the system will require more MMIO space than what the system can allocate within 32 bits of address space. When that occurs, those option cards that could not be assigned MMIO address space (because there was not enough left) will be unavailable for use.