Thursday, February 12th 2009
Phenom II AM3 Plagued with DDR3-1333 Issue
Barely a week into the introduction of the DDR3-supportive AM3 socket CPUs, the processors seem to be having design flaws. This, as circulated by AMD in its revision guide document for the 10h family of processors (found here, page 80). The issue, as described by AMD, centers around the DDR3 memory sub-system. On machines with more than one PC3-10600 (1333 MHz) memory module populating a memory channel, the users may experience unreliable operation. The company does not get into the specifics of the symptoms. This issue however, does not affect systems with a module per channel (one or two modules installed in the motherboard), and only those with three to four modules installed.
The AMD K10 memory controllers on AM3-socket processor provide a 128-bit wide memory interface (with DRAM Ganged mode enabled), which amount to two 64-bit wide memory channels. On most motherboards, four DIMM slots with two slots sharing a memory channel are present. With this issue, one is not recommended to use more than one DDR3-1333 memory module per channel. AMD recommends a quick fix for the issue for systems using more than one DDR3-1333 module per memory channel: to manually specify the memory to run at 533 MHz (1066 MHz DDR), and accordingly set DRAM timings. As a little compensation, one can tighten DRAM timings with the drop in frequency. AMD will fix this issue in the next stepping (sub-version) of the CPUs. The "x-factor" with this erratum revolves around DRAM voltage, a significant factor. One might note AMD saying "the processor memory subsystem may exhibit unreliable operation over the allowable VDDIO voltage range", which leads us to think if there is a potential workaround with adjusting the DRAM voltage beyond the allowable range (read: over-volting the memory). We hope to hear more from AMD on this.
UPDATE (02/13): AMD replied to the report, saying that work is in progress toward fixing the issue. While not getting into the specifics, AMD indicated to us that apart from addressing the issue, the company is also working toward something "which will make you 'feel cozy' about the DDR3 support". The statement is ambiguous, and is best left uninterpreted at this point in time.
The AMD K10 memory controllers on AM3-socket processor provide a 128-bit wide memory interface (with DRAM Ganged mode enabled), which amount to two 64-bit wide memory channels. On most motherboards, four DIMM slots with two slots sharing a memory channel are present. With this issue, one is not recommended to use more than one DDR3-1333 memory module per channel. AMD recommends a quick fix for the issue for systems using more than one DDR3-1333 module per memory channel: to manually specify the memory to run at 533 MHz (1066 MHz DDR), and accordingly set DRAM timings. As a little compensation, one can tighten DRAM timings with the drop in frequency. AMD will fix this issue in the next stepping (sub-version) of the CPUs. The "x-factor" with this erratum revolves around DRAM voltage, a significant factor. One might note AMD saying "the processor memory subsystem may exhibit unreliable operation over the allowable VDDIO voltage range", which leads us to think if there is a potential workaround with adjusting the DRAM voltage beyond the allowable range (read: over-volting the memory). We hope to hear more from AMD on this.
UPDATE (02/13): AMD replied to the report, saying that work is in progress toward fixing the issue. While not getting into the specifics, AMD indicated to us that apart from addressing the issue, the company is also working toward something "which will make you 'feel cozy' about the DDR3 support". The statement is ambiguous, and is best left uninterpreted at this point in time.
105 Comments on Phenom II AM3 Plagued with DDR3-1333 Issue
Lrn2read
It will get fixed. I'm just making jokes. Except the part about switching to Intel. I really am going intel.
It's not like ddr3 wont work at all, just an issue when using certain amount. It's not the end of the world people.
But I'll stick with what I said, untill ddr3 is more affordable and less problematic ill stick with ddr2.
AMD has a minor issue and it may be setting them back, but they still have a market even if it's the one some people might not want to be a part of. I still say phenom II is the ultimate lanbox cpu and if anyone contests that fine. DDR2-3 whatever, these processors have a purpose, and bugs will be fixed/put up for errata prior to a large scale launch.
Now if you all won't mind... if we're going to riot can we manage to swing by a Dunkin Donuts? I'm craving everything bagels.
And if I wanted more overclocking headroom, I'd probably buy at least ddr3-1600mhz RAM. And for 2x2GB of decent RAM at that speed (I don't mean the crappy 8/9 CAS modules), I'd be spending a little more (although MIR helps to make it only 20-30 more expensive than ddr3-1333, but I hate MIR). Hopefully the prices on those will go down to. It is nice to see that both Gigabyte AM3 boards natively support DDR3-1600, so maybe this issue is motherboard dependent? I wanna see someone use either of Gigabytes new AM3 boards and fill in all DIMM slots and see what happens.
from that I have 2 ideea :)
one is that will a cpu revision soon (aka stepping)
two it's possible to be only the amd marketing idea:), like the new stepping/version of cpu to give as a bug resolved and possible a higher speed for memory (1600/1800 or 2000 (if santa wants...) :)
also I want a hybrid mobo with ddr2 and ddr3 (evident optional) :)
However not all ram stick will cause incompatibility because it says "the users may experience unreliable operation" and hence you may have no problems with DDR3-1333 or faster memory, and therefore this issue is 100% hyperthetical and it might materalise that users having no problems whatso-ever! in essence it will vary user to user.