Why would you have problems with a system in which you installed three known good RIMMs?

All RIMM slots must be filled either with RIMM modules or CRIMM modules.

"23. Fill 'er up. Leaving a memory slot empty is not a problem as long as you install DIMMs. If you install RIMMs in your system, however, then you need to make sure every slot is full. No, you don't have to buy more of the pricey Rambus memory modules; simply use a pair of CRIMMs (continuity RIMMs), as they're called, to plug the empty memory slots on the motherboard. You can buy CRIMMs for $10 to $15 each from computer retailers. Failing to fill empty Rambus memory slots with CRIMMs will result in a computer that doesn't boot."

Taken from http://www.smartcomputing.com/editorial/article.asp?article=articles/archive/l0909/27l09/27l09.asp&guid=