Your memory modules are likely the problem.
The reason RDRAM is so expensive, is that there is none... It has not been manufactured for years and due to court decisions, it cannot be manufactured.
The RDRAM was the coming thing when it first came out... It was expensive to make, but it worked better than anything available at the time. The makers quickly became very rich.
But some illegalities were discovered... I cannot remember what... but I think they had to do with patten infringement or misrepresentation of the existing memory design. The designers and makers were taken to court where they lost bigtime for fraud and theft, and manufacturing of their design was shut down for good and forever... no time to stockpile.
Dell had RDRAM on about 12 machines, as did HP, Compaq, and Gateway.
The fix requires a new motherboard, and that is the best way to deal with it. You can buy a Dell GX 620, GX 260, GX 270, or GX 280 that will usually fit... and there are other Dell boards that will fit... They are found on eBay and PCSurplusonline for $70 to $130... depending on your lucky day... then Regular DDR and DDR2 memory will fit up to 2 GB for cheap prices.