How will AMD's eventual switch to DDR3 only IMCs effect tolerance to high vDIMM?

[Plimogz]

Evening all,

I was just thinking about how great it would be to be able to upgrade my AM3 system with a new CPU once bulldozer eventually comes out. Only I then remembered that I read somewhere that AMD's current crop of AM3 chips have good tolerence to relatively high DDR3 voltages on account of their also having DDR2 capability... Seeing as how AMD will likely drop DDR2 backward compatibility before moving away from DDR3 altogether, does anyone think that I'll be able to get away with keeping my current high voltage DDR3 (specced 1.9v) if, or rather when, AMD goes with a DDR3 only IMC on it's upcoming chips?

 

[lopri]

I think the upcoming platform will be even more oriented for lower voltage DIMMs. 1.35V is currently considered low, and I think 1.2V DIMMs are on their way.

I'd personally sell those sticks. If that's not feasible then just use them with what's compatible for now. There is no guarantee they'll work on future platforms.

 

[Triskain]

If you look inside AMD's technical docs, you'll see that the maximum allowed vDIMM for current PhII CPU's is 1,6V, so you are already over spec right now.

 

[Ben90]

Not to mention I don't think Bulldozer will be AM3, or at least the full version of it won't be AM3.

 

[richierich1212]

Not to mention I don't think Bulldozer will be AM3, or at least the full version of it won't be AM3.

Zambezi will be AM3+

 

[heyheybooboo]

JEDEC Publishes Widely Anticipated DDR3L Low Voltage Memory Standard
July 26, 2010

... Continuing the evolution of DDR3 as the dominant DRAM standard today, DDR3L will enable a significant reduction in power consumption for a broad range of products that utilize memory; including laptops, desktops, servers, networking systems and a wide array of consumer electronics products ...

Called DDR3L for DDR3 Low Voltage, devices adhering to the new standard will operate from a single 1.35V power supply voltage compared to 1.5V in existing devices. Under the new standard, DDR3L memory devices will be functionally compatible to DDR3 memory devices, but not all devices will be interoperable at both voltage ranges.

The DDR3L standard defines the operating characteristics for DDR3L memory devices, with the devices offering a reduction in power consumption of 15% or more as compared to DDR3 (and 40% as compared to DDR2), when operating at the same performance and load capacity.

This significant reduction in power consumption, especially in memory-intensive systems, will have dramatic benefits in areas such as power supply demand, system cooling requirements and potential packaging density.

--

 

[coffeejunkee]

Kingston and GSkill already offer these low voltage modules. Except they dont really enable a "significant reduction in power consumption", at least not for a single system. The difference was about 5 Watt or something. When talking about server parks it's a different matter ofcourse.

Now I can only speculate on how well Zambezi will handle high voltage ddr3. But I would like to mention that Intel changed the max vddq for Lynnfield cpu's from 1.65V to 1.8V, as can be seen here: http://download.intel.com/design/processor/datashts/322164.pdf, on page 65. Apparently the imc is tougher than we thought.