Help with pc4400 memory

[mymmaster]

Hello,

I'm playing with some Corsair pc4400 memory on my Athlon 3800 system (with Tyan K8E mobo) and I'm confused as to the results of some BIOS settings being changed.

I have the CPU frequency at 210MHz (10 Mhz higher then stock) and the Multiplier is 12x. So the CPU is running at 2520MHz. I am trying to get the memory to run at full DDR550 (275MHz) by changing around some frequencies.

*NOTE* the pic below is not what settings I'm using, it is just to give you an idea of what the menu I'm using looks like
http://www.bonafidereviews.com/articles/98/images/BIOSdramconfig.jpg

When I have the "Memclock index value" set to 200MHz in the BIOS, CPU-Z displays (under the memory menu) a Frequency of 210MHz with a FSB/DRAM ratio of CPU/12 (2520MHz/12x = 210MHz) so everything makes sense so far.

Then I change the "Memclock index value" to 250MHz, reboot and check CPU-Z. Now it says the Memory frequency is 140MHz with FSB/DRAM of CPU/18.

However even though the Memory frequency is now lower (140MHz compared to 210MHz) when I run benchmarks, the 140MHz speed (remember that CPU-Z says the mem. freq. is 140MHz when I set the "Memclock index value" to 250MHz) crushes the 210MHz speed. So it seems as though setting the "Memclock index value" to 250MHz is infact increasing the actual performance of the memory but the numbers aren't making sense to me.

What is the deal with the ratio going to CPU/18 ?? Maybe I'm not understanding what the Memclock index value even represents.

My goal is to 1) understand why this is happening and what it means and 2) ultimately to get the memory running at DDR550 (like it should be) without having to overclock the CPU that much (if this is possible).

Any help for the newbie is appreciated. If you know your stuff then just IM me (MSN: mymmaster@hotmail.com) and we can chat.

[shuRe]

i think the memory index thingy is the ram divider, so if you were to leave it at 200mhz then that would be 1:1 ratio with the htt speed. As for setting it to 250mhz values and your ram speed dropping try reading the manual.

What memory IC' are there in those corsair?

You would probably be best to set it to cas 2.5, trp 3, trcd 3, tras 8, or if that fails try cas 3 and that should be ok if the mem is ne good.

[mymmaster]

I think they use the Samsung TCCD but I'm not 100% on that.

The manual doesn't really contain any worth while info on that menu option.

ftp://ftp.tyan.com/manuals/m_s2865_110.pdf

I will try the timings suggestion and get back to you.

[Jupiler]

I moved the topic to the Xtreme Bandwith section, as it doesn't really belong in the XOC section.

[mymmaster]

I moved the topic to the Xtreme Bandwith section, as it doesn't really belong in the XOC section.


Oh ok. Sorry about that.

[mymmaster]

Ok, I tried setting them at 3-3-3-8. Didn't seem to work. I think the memory is rated for 3-4-4-8 anyway.

Let me clarify my problem.

I am trying to get PC4400 (DDR550) memory running on my Tyan K8E motherboard which supports DDR400 memory. The multiplier for the Athlon 3800+ is locked at 12. So the FSB is 200x12 = 2400MHz CPU speed. I have access to the CPU speed and the mentioned "Memclock index value" which I believe is the memory divider.

So how do I get the FSB to run at 275MHz? If I can do this then I would assume my memory can then run at the full DDR550 speed.

I think my main problem is that the multiplier is locked, so the CPU will have to run at crazy speeds in order to take advantage of the memory speed.

Any ideas?