MHZ 333 instead of 400 MHZ in bios pc 3200 400 ddr ram

[attila336]

Hi

 

I have installed 2 X 512 ddr PC 3200 400 plus a 1gig stick of ddr PC 3200 400 all of them corsair value select. Now if I run just 1 gig ( 2X 512) my bios shows 400MHZ if I run just the 1gig stick it shows 400MHZ but if I run all of them my Bios shows them at 333MHZ, why is this? My mother board is an Asus AS8-X with an AMD 64 X2 4200+ dual core processor.

 

Thanks

Attila

[RJLeong65]

Hi

 

I have installed 2 X 512 ddr PC 3200 400 plus a 1gig stick of ddr PC 3200 400 all of them corsair value select. Now if I run just 1 gig ( 2X 512) my bios shows 400MHZ if I run just the 1gig stick it shows 400MHZ but if I run all of them my Bios shows them at 333MHZ, why is this? My mother board is an Asus AS8-X with an AMD 64 X2 4200+ dual core processor.

 

Thanks

Attila

 

First of all, the Socket 939 memory controller is not designed to run with only three sticks of memory installed; it is designed to run with one, two or four (but not three) sticks of memory installed. If the system even ran at all under this configuration, not only did your memory speed drop to "DDR333" (actually, DDR314 with a 2.2GHz x2 4200+ processor since the processor's integrated memory controller operates at a set fraction of the processor's core speed), but your processor's memory controller also defaulted to single-channel-only mode (the Socket 939 memory controller was designed for dual-channel operation). This hurts overall memory performance even more than it would have had you filled all four memory slots with matching sticks of memory.

 

Second, DDR314 memory operation was also forced upon because with this single-channel operation, you have exceeded the total number of banks of installed memory supported for maximum-speed operation. One double-sided stick of memory already contains two banks of memory, and the Athlon 64 memory controller can properly support only four banks maximum of memory at full DDR400 speed.

 

Third, your 512MB sticks might have been double-sided (some newer packages of 512MB Value Select DDR1 memory are single-sided). If this is the case, you are mixing completely different IC chips, with completely different levels of IC densities, when you mix 512MB and 1GB sticks together. As such, the memory speed will default to a lower speed in order to ensure reliability. Plus, three double-sided sticks resulted in a total of six installed banks of memory, which exceeds the maximum number of banks the memory controller supports at full speed.