Is there any way to counter the BIOS automatically downclocking Ram?

[SunnyD]

I recently acquired a new stick of 1gig PC3200 ram, good stuff. 2.5-3-3-7 at 400MHz. However, I also had a stick of Corsair 512meg PC3200 which I don't really want to remove. Both modules are double sided.

The problem I have, the motherboard, a DFI Infinity NF4X automatically drops the Ram speed to 333MHz when 2 double sided modules are used. Actually, CPU-Z is showing the Ram clock at 160MHz.

In any event, how much success, and more importantly HOW would I run my memory at 400MHz in this configuration? Is this a card lock sort of thing that I am not going to be able to change?

The CPU is a Palermo core Sempron.

 

[alanore]

Your processors memory controller doesnt support 3 sticks of RAM running at full speed.

If you want to get them back up to speed you will have to overclock, but then you might have problems with the RAM as your processors memory controller can handle three sticks at 400MHz, you'll have to see if its able to by using a testing utility like memtest86. You cna make a bootable floopy which will test the RAM for errors at the set frequency.

http://www.memtest86.com/

 

[Peter]

It isn't that the memory controller "doesn't support" something here (although this is the layman's common view) - it's electrical limitations of DDR RAM operation itself. The properties of a highly loaded DDR RAM bus typically* don't allow safe 200 MHz operation. Parasitic capacitance, as you add chips, connectors, and lengths of trace, causes signal degradation. DDR400 has been calculated for single-DIMM operation, DDR333 for two, DDR266 for three.

You are getting 160 MHz because AMD64 processors divide RAM speed down from CPU core clock. So with e.g. a 1600 MHz processor, the closest fit for DDR333 is CPU/10, which amounts to 160 MHz.

*YMMV.

 

[SunnyD]

Originally posted by: Peter
It isn't that the memory controller "doesn't support" something here (although this is the layman's common view) - it's electrical limitations of DDR RAM operation itself. The properties of a highly loaded DDR RAM bus typically* don't allow safe 200 MHz operation. Parasitic capacitance, as you add chips, connectors, and lengths of trace, causes signal degradation. DDR400 has been calculated for single-DIMM operation, DDR333 for two, DDR266 for three.

You are getting 160 MHz because AMD64 processors divide RAM speed down from CPU core clock. So with e.g. a 1600 MHz processor, the closest fit for DDR333 is CPU/10, which amounts to 160 MHz.

*YMMV.

So the 4th bank is what's killing it. If I were to use 1 double sided and 1 single sided, it would run at 400MHz as per the motherboard spec (it's tabled in the mobo manual).

I would venture a guess that 4 banks (2 double sided modules) could run 400MHz, but pushing the limit. Again, the question in, is there any idea if it's physically possible to override in the BIOS or is this limiting factor something that is enforced permanently?