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DDR-2: The Memory of Tomorrow? December 31, 2003 The Heat is On, Literally and Figuratively One issue that continues to plague DDR-2 is heat, and not the good kind. In video-card comparisons, similarly-rated DDR and DDR-2 BGA modules exhibited strikingly different temperatures -- while ATI and Nvidia cards sporting standard DDR may be warm to the touch, you want to keep your fingers from getting anywhere near their DDR-2 counterparts' hefty heat sinks. This may not yield a direct parallel in larger, more-heat-spreader-surface-area desktop modules, but it does indicate that boosting the data fetch rate produces additional heat. This has created a virtual requirement for DDR-2 production to hit smaller process technologies in order to remain viable in the desktop arena. Top-end DDR-2 modules are currently being produced using an 0.10-micron process, with the target for a mass-market launch being 90-nanometer or 0.09-micron. The smaller process not only facilitates lower heat levels, but allows higher manufacturing yields per wafer, i.e., lower production costs. Of course, manufacturing improvements that benefit potential DDR-2 production are good news for standard DDR, as well. The similar core designs of DDR and DDR-2 have spurred a game of cat-and-mouse between the two technologies; memory makers have been working hard to achieve ever-shrinking die sizes, and -- with DDR-2 not coming to market as quickly as anticipated a year ago -- have shifted these into DDR production instead. When DDR-2 was first announced, standard DDR was using 0.13-micron process technology, but due to heavy competition, it's now common to find DDR built on an 0.10-micron line. Since DDR already runs cooler than DDR-2, the ability to use these "designed with DDR-2 in mind" die sizes has led to increased DDR speeds -- decreasing the relative market advantage of DDR-2 even before its mainstream debut. Again, check out what those gaming enthusiasts are buying: Memory manufacturers expected to release DDR-2/533 as a natural successor to DDR400/PC3200, but now we've got 533MHz (PC4200) DDR for sale in the mass market, with overclockers already moving on to DDR550 and DDR566, and talk of 600MHz DDR speeds right around the corner. Technology waits for no man, and that seems doubly true of system memory. Big-Brand Support Intel has been the first CPU (as opposed to graphics-processor) vendor to endorse DDR-2: its upcoming "Grantsdale" chipset for the "Prescott" Pentium 4 successor will feature dual-channel DDR-2/533 memory support, which should match up nicely with the proposed step from an 800MHz to 1066MHz front-side bus. Since Grantsdale will support a new CPU package and higher bus speed, Intel is unlikely to add DDR-2 support to existing Pentium 4 platforms -- and moreover, having obviously learned a hard lesson with RDRAM, will offer regular DDR compatibility in Grantsdale as well. This may just be smart business, but it could also mean Intel is keeping its options open until the real-world DDR-2 verdict is in. Portable PCs, however, are a segment in which DDR-2 promises to yield significant returns, and Intel is expected to move its Centrino platforms in this direction. The lower 1.8V requirement and relatively slower core speeds mean DDR-2 modules could produce less heat and use less battery power than standard DDR. The current plan is to institute a dual-channel DDR-2 architecture for notebook memory. AMD, whose 64-bit processors incorporate the memory controller that Intel leaves in the traditional place on the chipset, is more of a dark horse when it comes to DDR-2. The company has said it will offer Athlon 64 support sometime in the future, but the question remains of how much work needs to be done at the processor level; DDR-2 is command-compliant with DDR, so depending on the Athlon 64/Opteron core architecture, it could be an easy (or difficult) switch to implement an on-chip DDR-2 controller. There's also the option of turning the CPU's integrated memory controller off and using a secondary chipset for memory support, though the performance benefits of going this route for DDR-2 are questionable. DDR-2 may be the designated heir to today's desktop memory, but it brings a great deal of questions to the table. This is not the usual upgrade, with performance benefits pushing aside other factors; instead, DDR-2 represents a series of the tradeoffs that will need to be fully evaluated. The prospect of more performance at lower production costs certainly appeals to manufacturers, but real-world latencies, throughput, and heat production are still unknown. Maybe we should all follow Intel's lead and hedge our bets accordingly.