Complete A64 Memory Divider Table

[jlccarv]

Sorry Oskar...but I don't think this chart is accurate. Why didn't I gain bandwidth at the same HTT speed by changing to a "solid" multi ???

Lets bust up another myth or get to the bottom of it...

-Holly

http://xtremesystems.org/forums/show...d=1#post613669

RE: Your linked post...

CPU is 9.5*280=2660, with a 9.5 CPU multi the Memory is 2660/10 = 266

CPU is 9.0*280=2520, with a 9.0 CPU multi the Memory is 2520/9= 280

You have 140MHz extra clock on the CPU with the 9.5 CPU multi. That would give you the increase in the Buffered bandwith. Remember that CPU clock affects buffered bandwith...

[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.

[jlccarv]

Also...If it's true, I can run Prime all day long at 2.5,3,7,3 at 266HTT. I got instant Prime AND SuperPi errors the minute I tried 2.5,3,7,3 at HTT280 with BOTH 9x and 9.5x multis.

Have you considered that its your high HTT that maybe the cause for your errors in prime and superpi at 280HTT. Or even your HTT multiplier maybe too high...

[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...

[CodeRed]

It may, but not unbuffered. I saw no improvement going to ANY solid multi compared to an x.5 one.

Also...If it's true, I can run Prime all day long at 2.5,3,7,3 at 266HTT. I got instant Prime AND SuperPi errors the minute I tried 2.5,3,7,3 at HTT280 with BOTH 9x and 9.5x multis.


Again...I think that the table is either outdated, mis-interpreted or simply BS...I simply have found zero evidence that I'm losing either HTT speed or bandwidth within a variety of x.5 multi combinations compared to their "solid" brethren.

You must be the only one that doesnt believe in the 0.5x multi thing. Here are some pifast tests that show the multi is being rounded up:

2690 MHz (10x269) 43.38 sec
2689 MHz (10.5x259) 43.89 sec
2692 MHz (11x244) 43.89 sec
2689 MHz (11.5x233) 44.38 sec
2691 MHz (12x224) 44.39 sec

As you can see the 10.5 result is the same as the 11x result and so too with 11.5x == 12x


There is no doubt that the mem controller rounds up the 0.5x multipliers.

[hollywood]

You must be the only one that doesnt believe in the 0.5x multi thing. Here are some pifast tests that show the multi is being rounded up:

2690 MHz (10x269) 43.38 sec
2689 MHz (10.5x259) 43.89 sec
2692 MHz (11x244) 43.89 sec
2689 MHz (11.5x233) 44.38 sec
2691 MHz (12x224) 44.39 sec

As you can see the 10.5 result is the same as the 11x result and so too with 11.5x == 12x


There is no doubt that the mem controller rounds up the 0.5x multipliers.

So now it rounds up ??? Everyone is saying that it rounds down...even that chart says it rounds down.

pfft...I'm getting a migrane...

[CodeRed]

So now it rounds up ??? Everyone is saying that it rounds down...even that chart says it rounds down.

pfft...I'm getting a migrane...

No the chart shows that it rounds up.

If it rounded the memory multi down then the mem speed would exceed the spec values of 200, 183, 166 etc etc. Thats why AMD had to implement it this way.

[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

[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

[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

[boblemagnifique]

hello

could I know has how much is my RAM really please ?

thank

[SpotTheCat]

as you can see, I have a really nice overclocker in my hands. The problem is I can't for the life of me get my memory to it's rated speed. The memory dividers in my bios are only 133, 166, and 200 (14, 11, 9)
my memory (corsair value PC3200 2.5cas) can only make it to about 205mhz, so right now I am using the 14 divider that gives me 186mhz memory, could I change it to 13 so I can have ~200mhz memory again?

[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