A RIMM-based machine fails to boot when a few RIMM slots are left open.
Cause: Intel’s 850 chipset motherboard includes RIMM sockets as a support for RDRAM. Usually, the board has four slots. RDRAM works in pairs, so for 256 MB, you will need two identical modules of 128 MB each and two ‘dummy’ modules, or four modules of 64 MB each. The latter option will limit the scope of upgrading. Dummy’ modules are used to enable conductivity in empty sockets. If the sockets are left open, then the RIMM issues a failure error and the system won’t boot.
Solution: Keep the RIMM slots/sockets occupied with compatible RDRAM or ‘dummy’ (or conductivity) modules. Also make sure the modules in the pair are identical.