DDR2 is overstretched beyond its Gigahertz limits

THE ORIGINAL DDR memory was specified at 266MHz throughput and ended up at 400MHz officialy, with vendors like OCZ or Corsair going up to 600MHz in selected parts. Now, the DDR2 official spec is frozen at 800MHz, but there are plenty of parts running at 1066MHz and above for 'enthusiasts'.

Now, in the famous press kit that Nvidia sent to the journalists on the Nforce 680i a month ago, for the first time, another new speed grade was mentioned - an 'upcoming version' of Corsair Dominator overclocker's memory, running at no less than PC9600, or DDR2-1200 throughput speed! And, there is even talk of extending the DDR2 spec to 1066MHz officially.

Realistically, you probably couldn't run that memory at this speed with anything less than 2.2 volts supply - far higher (and hotter) than the 1.8 volt specificiation of original DDR2 or the selected dies used on those DIMMs. In many cases, 2.3 volts are recommended, coming close to the old 2.5 volt DDR1 voltage levels. Are we going too far with DDR2, instead of early switching to the 1.5 volt DDR3 at the 1333MHz throughput?

Well, DDR3 is still in the early production stages, partly because there was no demand - since there are no mainstream chipsets supporting it - yet. On the AMD side, we have to wait for the AM3 socket with K8L core, another nine months or so away. Either should provide for up to DDR3-1600 speeds at the 1.5v stock voltage. But the first, late-2007 "Altair FX" units only come with an improved DDR2 dual-channel controller, now with the official 1066 speed.

On the Intel side, an upcoming "non-Intel" graphics workstation-oriented chipset for its dual-FSB, dual-socket Woodcrest/Clovertown, would be a good candidate for initial DDR3 support - dual-channel DDR3-1333 is a nice match for dual 1333 FSB paths, isn't it? And, if you overclock each FSB to 1600MHz, well DDR3 supports 1600MHz speed too, out of the box.

Interestingly, compared to the initial latency performance loss shown when moving from DDR1 to DDR2 two years ago (DDR1-400 CL2 vs DDR2-533 CL4), there wouldn't be such a loss on the DDR2 to DDR3 move. Even the first DDR3-1333 parts are expected to have CL6 latency right at the start, with many able to provide CL5 too, or CL6 at DDR3-1600 soon after - remember, these are generic DIMMs, not the hand-picked, specially-designed Corsair, OCZ or Geil parts. And, again, all that at 1.5 volts for lower power and lower heat... µ