Hi jim kelley; You wrote: "It is the impact on cost of the motherboard and not just the IC package that is crucial. You seem to be forgetting that over and over again."
I didn't forget about pin savings on the motherboard. The very fact that you would assume that there are any, is an indication that you don't have the slightest notion of what the real costs of motherboard manufacturing are. I would guess that there are very few people who read this board who are in a position to supply the costs and numbers. So lets count pins and calculate costs, and see just how cheap this RDRAM is to implement, as far as PCB costs go...
DDR DIMMs and RDRAM RIMMs have the same pin count, while SDR DIMMs have fewer pins:
micron.com
Given that DIMMs are available with higher densities, RDRAM loses.
DDR and SDR DIMMs will have more pins at the controller chip, but that is only one chip, while a motherboard takes multiple DIMMs or RIMMs. Total number of pins per 64-bit interface is somewhere around 100 to 200. (Given that 64-bit wide SDRAMs are packaged in a 108 pin uBGA, I would tend towards the low end of that range.) An RDRAM interface is about 50 pins, so the difference is certainly less than 150 pins. How significant are 150 pads on a motherboard?
Cost of pads on a board (quantity 10000, quote from an on-line PCB house) is $2.82 per 1000 pads per board. So the cost for adding 150 pads is around $0.42 per board, smaller in larger quantities. This is a small fraction of the cost of a single RIMM heat sink, which has to be included with every RIMM module.
The basic fact is that mom and pop have been fooled by this hype because they are not in a position to make the calculations. This statement applies to pretty much every facet of this ongoing farce. The buyers of this stock are in way over their heads when it comes to understanding technological advantages. They think in words, engineers think in numbers. Rambus is only a story stock, and the story gets into big trouble this summer...
-- Carl
P.S. As long as I'm on the subject, we should note that DDR and SDR DIMMs are a lot cheaper to make than RIMMs, ignoring the cost of the chips, as RIMMs are currently 6 or 8 layer boards. In addition, RDRAM motherboard require extensive testing, and so are inherently more expensive than the usual. It just isn't close, all Rambus hype to the contrary. And reduced costs due to larger production isn't going to help, the high costs are built in. |
