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TWIN2X4096-8500C5DF not reading as 1066 correctly


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For some reason, I can't get my RAM up to speed of 1066. I've tried manually changing it in the BIOS by changing:


CA5 Latency to 5


tRCD to 5


tRP to 5


And tRAS to 15, as well as setting the DDR Voltage to 2.1v


I left the memory speed on auto, because I was not able to select 1066 from the menu. The highest it would allow me to select was 800.


I have submitted a screenshot of cpu-z here. As you can see, it's actually running SLOWER than 800. I am using the M3A79-T Deluxe motherboard. I would appreciate any help, thank you!



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As I tried to say numerous times, that "800MHz" rating (or "1066MHz") is the effective speed (the true I/O clock speed of DDR2 memory will always be half of the effective speed). But the speed in the "Memory" tab of your CPU-Z screenshot reflects the true I/O clock speed of the memory (with your particular CPU). The x2 6000+ cannot run DDR2-800 memory at its full speed due to the idiosyncrasies of the on-die AMD memory controller (the divider ratio between the memory clock and the CPU core clock must be 1:x, where x is an integer value and not a floating-point decimal value). In your case, 3000 divided by 400 would have given you a divider ratio of 1:7.5, which the AMD memory controller does not allow (the AMD divider ratio must be either 1:7 or 1:8, but not in between). Since you cannot set your memory speed above DDR2-800 speed even manually, the memory speed at the 800 speed defaulted to the nearest available speed without exceeding the official specs for the set speed, which resulted in a divider ratio of 1:8, which gave you a true memory clock speed of 375MHz/DDR2-750 or thereabouts (it actually read 376.2MHz, or DDR2-752.4, due to your motherboard overclocking slightly at default settings).


In addition, you have an AM2 processor, not an AM2+ processor. DDR2-1066 memory is supported only with certain models of the AM2+ CPUs (Phenoms only) on your motherboard - and DDR2-1066 support is limited to only one module per channel. With an AM2 (without the plus) CPU such as yours, the memory speed support is limited to DDR2-800 maximum (subject to the memory controller idiosyncrasies described in the previous paragraph).

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yep! that's correct, you need AM+ like a Phenom X4.


I got little hard time to set my memory because you need to set one or one pair perfectly with the old good method I.E. manualy :biggrin:


But I Now I'm able to run 8Go (2 kit) 4X twin2X4096-8500C5DF with this board.



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Also this has been posted so many times I cant even remember.

With 4 modules DDR667 or DDR800 would be suggested and set the memory Voltage to 2.1 Volts and set the NB/MCH/SPP Voltage to +.2 Volts over default.
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