|First Thoughts - Corsair's DDR3-1333MHz DHX modules:
The modules look great, perform as you'd expect but most importantly scale really very well. We are sure, given a more mature motherboard (and BIOS), we could hit 1600MHz with these. It's worth remembering that they are engineering samples so retail versions may not clock to the same levels however, but the bandwidth seems to really take off as you hit 1333MHz.
At the 1.5-1.85V we ran them at the modules stayed very cool throughout. We were able to drop the latencies down significantly at DDR3-800, but as you increase the clock speed, latency unfortunately exponentiates upwards more than DDR2.
First Thoughts - DDR3 Performance:
A cynical way to will look at this would be to decide that they're increasing the memory speeds just for the sake of it. Intel's Core 2 processors don't need huge amounts of memory bandwidth, but Intel (and AMD) need DDR3 in order to keep the motherboard manufacturers happy so they can flog you yet another chipset. So, why not concentrate on improving the quality of DDR2 and running it at lower latencies?
Well, the multi-core era is bearing ever closer and thus the need for memory bandwidth will become ever greater. In time, DDR3 will evolve into a product that leaves DDR2 far behind, but that won't happen until it has reached close to its physical limits in a few years. It's simple economic laws though: the quantity of DDR3 sales will be low, so the price will be high and most people are still investing in DDR2.
The DRAM manufacturers have to keep investing in DDR3 (and beyond) to make sure they reach a point (we're probably looking at somewhere north of 1600MHz) where it's actually worthwhile and you get the appreciable performance increase over DDR2. We're in the awkward "teenage" stage, with growing pains, spots and a voice sporadically breaking.
As far as DDR3-1066MHz goes it isn't even worth considering, your first port of call should be the 1333MHz modules. It's the same situation as it was back in the DDR and DDR2 days, where people we told to ignore the pointless PC-1600 DDR and PC-3200 DDR2 in favour of the slightly faster modules that actually made a bit of a difference. But still, unless you're hammering the memory like in video encoding exercises you're not going to see a performance increase. If anything, it'll get worse in other cases, as shown by our MP3 decoding tests.
Combine both the "teenage stage" and "first chipset syndrome", where you get the functionality but not performance until the second generation: then you sit in an unideal situation. Amongst other things DDR3 does bring better general prefetch performance and lower power usage for mobile situations, but it's not yet going to give you a better computing experience.
Perhaps AMD's AM3 socket (when it arrives next year), as well as future multi-core CPUs from both camps, will offer a greater need for tons of memory bandwidth. However, the current situation means that sticking with DDR2 is the best option for the foreseeable future: there's far more competition providing better prices, better engineered BIOSes and chipsets currently available. Therefore, unless you have