What is the ratio for the "DDR166" Memory Setting

[Slaimus]

System: A64 3000 Winchester w/K8N Neo2

The BIOS acts as if it is a 5:6 ratio, which makes sense since 166 is 5/6 of 200. It shows 200MHz memory for 240MHz bus on the POST screen. However, CPU-Z shows my memory at 196.4MHz with a CPU/11.0 divider, which means the ratio is actually 9:11.
Is CPU-Z confused or is there something funky going on with the multipliers?

 

[Peter]

There are no such ratios as the BIOS pretends. That's just to keep users from learning new stuff.

As you observed, AMD64 architecture divides the RAM speed down from the CPU frequency. This in turn is multiplied up from the base frequency; the HTT freq is independently multiplied up from the same base frequency.

So, you got base frequency at 240, CPU at 2160 MHz. To get RAM speed near (but below) 200, CPU/11 is the correct divider. Nothing wrong with that. There is no FSB.

 

[Slaimus]

Interesting... So is there no way to directly manipulate the memory divider but at the mercy of however MSI decides it should be derived?

 

[Icepick]

No, you can set it in BIOS. Go to Cell Menu --> DRAM settings IIRC.

 

[Peter]

Originally posted by: Slaimus
Interesting... So is there no way to directly manipulate the memory divider but at the mercy of however MSI decides it should be derived?

Yes of course there is - but not the way you're used to from chipset-centric architectures.

AMD64 divides the RAM frequency down from core frequency. So with your 2160 MHz CPU and 166 MHz DDR RAM, you'll have to go for CPU/13. Well written BIOSes should be able to come up with that automatically, if yours doesn't, then you now know what to set manually.

 

[Slaimus]

I guess what I meant to say is whether it is possible to directly set the memory multiplier, without leaving it to the BIOS to figure out which one to set. Basically with my 3000 at DDR200, it sets the memory multiplier to 9x, while DDR166 sets it to 11x. Can I, for example, set it to 10x somehow?

 

[Peter]

If there's a manual control for this in your BIOS setup, then yes. Else, no.