Well, first, it is “30% lower power or x2 faster then GDDR5”. At twice the speed it is much much more power-hungry…
Some good reasons for not using XDR2:
[*]Expensive.
[*]Proprietary design, while GDDR5 is a JEDEC standard.
[*]Is tied to only one supplier, Rambus. GDDR5 is produced by most DRAM companies, which compete against each other, keeping prices low and supplies high.
[*]Not backward-compatible. GDDR5 I/O can be easily reconfigured for GDDR3 or DDR3 operation, enabling low-cost derivatives and smooth transitions between memory technologies following market demand and price fluctuations. XDR2 uses differential signaling, which is a completely different and incompatible I/O standard.
[*]Requires twice more data pins than GDDR5 because of differential signaling, which more or less eliminates its speed and power advantage…
“The XDRâ„¢2 memory architecture is the world’s fastest memory system solution capable of providing twice the peak bandwidth per device when compared to a GDDR5-based system. Further, the XDR2 memory architecture delivers this performance at 30% lower power than GDDR5 at equivalent bandwidth.”
and if its “OR”, its still better. they can get the same speed and eat alot less power!
If there is only one manufacturer (Rambus) then they can price it at whatever they want and you have to pay for it. Even large corporations have a limit to the amount that they are willing to pay for the extra speed. At some point, it’s more worthwhile just to buy some extra cards with the cheaper GDDR3/5 memory. If you don’t believe me, search Google for “rambus monopoly”…they were investigated by the US government a few years back for abusing their monopolistic market share when Intel was using them for the first Pentium 4’s.
Nvidia is going to have to pay someone (or some people) to design new PCB’s that support the new memory. Those people don’t work cheap. The new PCB’s will have many more traces, so they won’t be cheap either. Nvidia will pass those costs along to the consumer, driving up the cost of the board yet again. Add in the overhead cost of having the new PCB produced (since we’re talking about only producing a few boards, there will be a significant overhead cost per board to set up manufacturing for them), and the price goes up yet again.