There is an incompatibility between DDR3-1333 memory and cpu socket AM3

[shilong]

"The use of more than 1 module memory for DDR3-1333 channel can lead to instability of operation with CPU Socket AM3"


In recent days, AMD has made its first desktop cpu for DDR3 memories, talk about solutions AM3 socket, in the form of models II Phenom X4 and Phenom X3 II, currently commercially available in the following versions:

These processors are also compatible with motherboards Socket AM2 +, provided that the motherboard has been upgraded to bios level: this will leave room for use in combination with DDR2 memory up to DDR2-1066 standard.

For compatibility with the DDR3 memory standard maximum certified by AMD is that DDR3-133 3, albeit with some limitations. Looking at the datasheet of the new processors, in fact, showed an incompatibility with the use of memory modules DDR3-1333 in number greater than 1 per channel. If we adopt a configuration of this type, it is possible that the system manifests behavior outlier.

DDR3-1333 Configurations with Two DIMMs per Channel May Experience Unreliable Operation

Description
In systems with more than one DDR3-1333 unbuffered DIMMs on a channel, the processor memory subsystem may exhibit unreliable operation over the allowable VDDIO voltage range.
This erratum does not apply to DDR3-1333 configurations when only one DIMM per channel is populated.

Potential Effect on System
Memory system failure leading to unpredictable system behavior.

Suggested Workaround
In a configuration where two unbuffered DDR3-1333 DIMMs are populated on one channel, the BIOS should considered DDR3-1333 memory system operation to 533 MHz (DDR3-1066) by setting the DRAM Configuration High Register [MemClkFreq] (F2x [1 0] 94 [2:0]) to 100b and adjusting memory subsystem timing parameters accordingly.

AMD confirmed that more than one using DDR3-1333 module for channel instability is observable in the system. A viable solution is to decrease the clock frequency of memory to DDR3-1066, by less conservative memory timings in order to balance the decrease in clock frequency. Instability 1.333 MHz clock seems to be linked to the supply voltage of memory, at least read what it says in the datasheet, a solution could be to overvoltage slightly more than the specific memories, in order to seek greater stability. No problem occurs when you use a form DDR3-1333 memory for each channel, and then you configure the system with a total of two memory modules.

[Kane01]

seems like a pretty serious bug. MDO is not the best way to inaugurate this new CPU. Already it appears inconvenient to match CPU-ram DDR3 because of cost of purchase. If we are certain limitations, will be even harder to choose than DDR2.

[Alchmey]

If this is the fact that the performance of current DDR3 does not deviate much from the DDR2, the circle closes.

It would be good that this big bug was corrected.

[Arley]

Leaving aside the speech convenient or less from the economic point of view, I think a bug is solved with a bios update ..

[Aditya kumar]

It was the same thing happened years ago, if you remember, and in fact appeared in the BIOS option "flexibility" affixed to force the memories to work at slightly reduced frequency (from 166 to 133 or 200 to 166): nothing particularly worrying.