Complete A64 Memory Divider Table

[Badge56]

Am I reading this correctly? The RAM will not go over 200 mhz no matter what divider you use on the CPU?

I am at 2450 (10X245) RAM is DDR33 so its at 204 mhz
at 2400 (10X240) RAM at DDR333 it was also at 204

Will not post if RAM at DDR400

Explain please.... this is NOT clear yet.

[hollywood]

Am I reading this correctly? The RAM will not go over 200 mhz no matter what divider you use on the CPU?

I am at 2450 (10X245) RAM is DDR33 so its at 204 mhz
at 2400 (10X240) RAM at DDR333 it was also at 204

Will not post if RAM at DDR400

Explain please.... this is NOT clear yet.

the 200 means 1:1 ratio to HTT speed...

[hollywood]

Yeah...I get it...

CPU at 9.5 multi x 280HTT = 2660

Mem multi goes to 10

divide CPU speed by 10 = 266

Means "real" HTT is only 266.

I was wrong and stand corrected, thank you for helping me understand CodeRed and jlccarv.

So now the question is...how high can I get at only 9x, cause 10x divider put my mem too low...

[Badge56]

Ok, let me get this straight.
My current set up is 2450mhz (245X10) DDR333
System shows 2450mhz CPU and 204 mhz RAM

According to the chart, using DDR333 (aka 166 mhz) the divider should be 12 and it is according to CPUz but my RAM is running 204mhz ????? According to the chart is should run 160 mhz

What am I not understanding?

[papatsonis]

no , its correct at 204, 10x *(200/166)=12 = your ram divider, 2450/12 =204,....

[Badge56]

Yep that part is clear. Why does the chart show Real dram frequency = 166,67 for 2500? Why not 208 ( 2500/12 ) Why the 12.5 divider?
According to CPUz I am now at 2500 mhz and RAN 208

[bias_hjorth]

Hmm I am having a hard to figuring out what actual speed my modules are running. Hope someone cloud clerify this.

11 x 274 (with the 183divider) - Buggy eh? Or is it just me

[CodeRed]

Hmm I am having a hard to figuring out what actual speed my modules are running. Hope someone cloud clerify this.

11 x 274 (with the 183divider) - Buggy eh? Or is it just me

mem multiplier is 200*11/183.333 = 12 exactly

so mem speed is 11x274/12 = 251.67 MHz

[bias_hjorth]

:thumbsup: thx

Although I may have hit some kind of bug cause my memory cant run at that speed. They usually max out at 245 and is very unstable up from 240.

*edit if I bootup at 166mhz mem speed the bios shows me the correct 227mhz at the 274 x 11. But cpu´z and everrest shows me 217mhz.. Seems fishy

* edit 2: Well after seeing the no 1 table again I think you may have miscalculated.
11 x 200 = 183 divider choosen = ~ 169mhz real speed
------------

11 x 200 = 2200 / 169 = ~ 13
11 x 274 = 3014 / 13 = ~ 231

Or can I be wrong here. Btw. notice according to the no 1. chart the 11.5 multi is faster than 11 and 12

[CodeRed]

[QUOTE=bias_hjorth* edit 2: Well after seeing the no 1 table again I think you may have miscalculated.
11 x 200 = 183 divider choosen = ~ 169mhz real speed
------------

11 x 200 = 2200 / 169 = ~ 13
11 x 274 = 3014 / 13 = ~ 231

Or can I be wrong here. Btw. notice according to the no 1. chart the 11.5 multi is faster than 11 and 12 [/QUOTE]

I didnt use the table I used the formula:

mem multi = ceil(200 * CPU multi / mem speed ratio)

Maybe it is 13x instead of 12x since its on the edge. Might be a good idea to test with something like pifast

try 13x200 1:1 vs 12x217 1:1 vs 11x236 @ 183 and see which are equal.

[Formann]

Does this make it any easier?

Im pretty sure this is correct.

http://xtremesystems.org/forums/show...459#post628459

[Capt MonkeyBoy]

hi'ya



i made an App using

13 * 200 / 166 = 15,66 ---> = 16

2600 / 16 = 162,5MHz

and it fits the table's on the first page of this thread, with all it's calculations at 200mhz, but it differs from Z-Cpu and the bios at higher HTT settings..??

the way the calculation is worked out it will hold the Ram at the frequ you set the divider at.....

like this

13 * 250 / 166 = 19.57 ---> = 20

3250 / 20 = 162,5MHz

is this right....or will it float up with the HTT,,,,,



cheers

[AKRedneck]

Or try the spreadsheet cause it can't get any easier...complete with graphs, etc in the separate sheets. Plug yer numbers and it does the rest..

http://www.xtremesystems.org/forums/...ad.php?t=49393

[papatsonis]

yes, eventhough till yesterday, i was thinking that the ratio was 11/12 , now i think its 10/11 , cause a person i know was bnchmarking at 11x297 with 183 divider, and no way (even he, admitted that) he could have his BH-5 at 3266/12=271.... more probably its 3266/13 , so its 11*(11/10)=12,1 rounded o 13

[brandinb]

lol for you guys having problems figuring this out go to oskars second table and find the multi you are using. then follow it to the right and go to the ration your using. then devide your total cpu mhz by that number for your final ram speed.
________
FeedMyLips

[bias_hjorth]

Yeah sure brandinb.. Thats the way to do it..
This is the correct way:


Ex
11multi x 200htt = 2200overall mhz / 169 from oscar_wu = ~ 13 mem divider.
11 x 274 = 3014 / 13 = ~ 231

[SpotTheCat]

I know how to calculate everything, but I don't know how to get a memory divider of 13 on my GA-K8NF-9
only options I can find are 133, 166, 200

[Unhooked]

i think CPuz too gives you the correct readings for ram
here is mine

[Orthogonal]

I know how to calculate everything, but I don't know how to get a memory divider of 13 on my GA-K8NF-9
only options I can find are 133, 166, 200

Unfortunately, not all motherboards give all the different multiplier options.

[Spajky]

How to know the real memory clock on AMD "K8" platform:

... { A64´s have a default clock reference [System Bus] at 2HGz & default mem. divider @ 10, while s.754 Sempron´s at 1,6GHz & divider of 8. That means for Example : running a 50% OC-ed 1,8GHz CPU @ 2,7GHz-(Htt-300MHz) : Sempron with mem.divider 9 & A64 with 11; real memory clock on first one is 267MHz, while on another is 273MHz, if your memory sticks can handle it } ! ...

So; for A64: Htt x [def.div(10) / mem.div.] = real mem.clock
& Sempron: Htt x [def.div.(8) / mem.div.] = real mem.clock

CPU-Z is not reliable on AMD "K8" platform showing memory clock (mem.divider is shown properly!)


My (research) article "about BENCH´ING MEMORY -real life"
with WinRAR´s built_in benchmark & hardware test" - on my site:
some tests/benchmarks & explanation HOW IT WORKS, is here directly:

http://freeweb.siol.net/jerman55/HP/benchMem.htm

[especially the yellow column is interesting!]
/sorry, I didn´t make any graphs/

Regards ...

[DarkManX_BG]

CPU-Z reads it right for me:
I run 300HTT, a multi of 8x and I want 250MHz memory speed. The 166 (5/6) divider should give me 250MHz. However:

200x8 / 166 = 9,xx -> 10
2400/10 = 240MHz memory speed
And that's what CPU-Z reads here...

[T_M]

*breaks out the shovel for some digging*....

Only thing i can find wrong with the table Oskar is that you spelt "Ratio" wrong
Apart from that is seems spot on for my own findings on 10x and 11x.

[ImportantAwareness89]

Ok, so Athlons use this type of divider setting, but Intels still use the simple FSB * ratio right? Only Athlons involve the whole ceiling, multiplier, etc...??

[lukija]

Hi. My first post here

I wrote small utility , you can grab it here:

http://users.yubc.net/~lukija/A64Info.rar

It is still unfinished, untested .... works well on my Winchester. Use it on your own risk. Yes, i know, it has stupid name (A64Info) You can tweak some values like in A64Tweaker and it also has built in calculator which calculates memory speed and I used Oskars table as a starting point.

But, I have one question regarding undocumented dividers. For example 180 ( from the DFI point of view). I'm not sure if it is 183.0 MHz or 183.33..... MHz. According to the table, it is 183.0 MHz. For example, you have 2200 MHz CPU (200 MHz x 11). And use 180 divider on DFI. If we look at the table or use calculator in A64Info we get divider 13 and memory speed of 169.23 MHz. But if we assume that 180 divider implies 183.33..... MHz then we get 12 divider and exactly 183.33..... MHz. It seems logical to me. It would be interesting to measure memory bandwidths in these two scenarios:

1) CPU Speed 2200MHz (220 MHz x 10). Using 166 divider we have 12 memory divider which finally gives 183.33 MHz memory speed. Measure bandwidth using Sandra or Everest. This bandwidth will be used as reference.

2) CPU Speed 2200MHz (200 MHz x 11). Using 180 divider we have:

a - 13 divider (if we assume thah upper limit for memory speed is 183.0 MHz) and memory speed of 169.23 MHz

b - 12 divider (if we assume that upper limit for memory speed is 183.33... MHz) and memory speed of 183.33... MHz

Comparing measured bandwidth in case 2 with one measured in case 1, we could see what is upper limit. If bandwidth in case 2 is equal (+/- few MB/s) to one in case 1 we can say that upper limit is 183.33... Mhz. If bandwidth in case 2 is lower ( because of 14 MHz lower memory speed) then one in case 1 we can say that upper limit is 183.0 MHz.

Required: CPU with at least 11 multi, mobo with 180 divider, Sandra, Everest.

Any ideas, suggestions, comments?

[ReelMonza]

Nice, will check your app later, can you please look at this