RAm speeds w/ OC

[sackynut]

so, ive been trying to get a better OC and i keep running into this RAM timings problem. basically, Its either 333mhz ram w/ a 2.5ghz CPU and 1000mhz HT

or 400mhz ram w/ 2.4ghz CPU & 960mhz HT. if I try to go to 2.5 at the regular RAM speed it fails because the ram cant handle 416 mhz.

so, I was thinking, and I was trying to figure out how my FSB and all that translated into my ram speed because it didnt make much sense to me.

so i was wondering if someone knew, or could help me figure out how the speeds and numbers translated.

heres the basic info:
(my ram goes by speeds, not dividers. )
CPU multiplyer for all = 10

HTT = 240
DDR speed = 166mhz
HT multi = 4

HT becomes = 960
CPU speed becomes = 2.4ghz
RAM speed becomes = 399mhz


Next scenario:
HTT = 250
DDR speed = 133mhz
Ht multi = 4

HT becomes = 1000mhz
CPU speed becomes 2.5ghz
RAm speed becomes = 333mhz

Last Scenario:
HTT = 250
DDR Speed = 166mhz
HT multi = 4

HT becomes 1000mhz
CPU speed becomes 2.5ghz
RAM speed becomes = 416mhz (unstable).

I figured out that the difference in speed from original speeds, and w/ the overclock on the first two was 67mhz. but the last one is 87. if someone could tell me or help me figure out this weird ass equation, it would help greatly. Im wondering how the FSB translates into extra speed on the RAM. thanks!

[LoD]

Re: RAm speeds w/ OC

HT speed doesnt matter, its not a bottleneck, anything in the 800-1000+ range is fine. As for memory its not much of a bottleneck either, DDR333 vs DDR400 wont make much of a difference.

try running a benchmark like 3dmark, or a game time demo, my huntch is 2.5ghz is faster at any memory divider.

Another thing, how high can your CPU go? 2.5ghz is a little quaint, i'm guessing you can push it to at least 2.6 if you wanted, I can get mine to 2.7 with slightly excessive voltage, but I can hold at 2.6 with only 1.42volts.

[LoD]

Re: RAm speeds w/ OC

Another thought... what kind of timings and what kind of memory specifically is your ram? Whats the model # etc....

216mhz IMO is not that much, most Value ram can take that, as long as your not pushing an excessive timings. Have you tried giving your ram more voltage?

[sackynut]

Re: RAm speeds w/ OC

1.42 volts at 2.6??!?!?!? geeeeeeeeeez.
anywas, i still was wondering how it translated into ram speed....i just wanna know the euqation or w/e.

and yes, at 2.9 volts, 415mhz, 2-3-3-6 timings its unstable.


EQUATION PLZ!!!

[LoD]

Re: RAm speeds w/ OC

Download this program its great... but BTW your numbers that you have already posted are correct.

http://www.forumdeluxx.de/forum/showthread.php?t=82491

[sackynut]

Re: RAm speeds w/ OC

no, i know they are. but im wondering HOW it gets those numbers. i dont see how going from 200-240 HT, and 4x HTT translates into an extra 67mhz on the ram...

[LoD]

Re: RAm speeds w/ OC

1.42 volts at 2.6??!?!?!? geeeeeeeeeez.
anywas, i still was wondering how it translated into ram speed....i just wanna know the euqation or w/e.

and yes, at 2.9 volts, 415mhz, 2-3-3-6 timings its unstable.


EQUATION PLZ!!!

What do you mean geeeeez?

Another thing, what type of memory is it, it might not be good at CAS2 overclocked. You could try CAs2.5 or CAs3 and i'm sure you can push the ram much further.

[LoD]

Re: RAm speeds w/ OC

no, i know they are. but im wondering HOW it gets those numbers. i dont see how going from 200-240 HT, and 4x HTT translates into an extra 67mhz on the ram...

Click the link to the A64memfreq program.

Or google it yourself.


EDIT: 4x HTT only affects the hypertransport speed, it has nothing to do with ram speed. Only your memory divider and "FSB" have effect on the ram speed.

[sackynut]

Re: RAm speeds w/ OC

its Corsair XMS, it bought it, and on newegg it was ddr400 , 2-3-3-6. of course, it migiht now do as good with a hhigher speed. but i still just want the equation =(

k ill download it, what does it do that site is in german.

[LoD]

Re: RAm speeds w/ OC

its Corsair XMS, it bought it, and on newegg it was ddr400 , 2-3-3-6. of course, it migiht now do as good with a hhigher speed. but i still just want the equation =(

k ill download it, what does it do that site is in german.

Where is the link to the ram? or what type of ram chips are on it? samsung UCCC, Infineon etc....

[sackynut]

Re: RAm speeds w/ OC

umm let me see:

http://www.newegg.com/Product/Product.asp?Item=N82E16820145449

[LoD]

Re: RAm speeds w/ OC

You have four sticks of that?

[sackynut]

Re: RAm speeds w/ OC

yupyup.


also a side note (since im not on my A64 computer): the equation plz =(.

[i made you]

Re: RAm speeds w/ OC

You need to change your tCAS to 2.5. Ram frequency is determined by CPU/divider. The divider is determined by the cpu multiplier and memory frequency setting.

[LoD]

Re: RAm speeds w/ OC

LOL You asked for it. I never manually calculate ram timings because its a royal B*tch.

http://www.dfi-street.com/forum/showpost.php?p=203167&postcount=3

I would just use the program.

Originally Posted by Sharp
How to calculate your memory frequency

Memory Frequency = (FSB x (CPU ratio)) / ] ((CPU ratio) x (FSB : DRAM ratio)) [

Ceiling function is shown with ][,
eg
]10.1[ = 11
]10.2[ = 11
]-6.2[ = -6
]-8.9[ = -8

For positive numbers always round up to the nearest whole number.
For negative numbers always round down (its actually still up) to the nearest whole number.

Big example
FSB = 290
CPU ratio = 7
DRAM:FSB ratio = 5:6, re-arrange to 6:5 (FSB : DRAM)

Using the formula,
Memory Frequency = (FSB x (CPU ratio)) / ] ((CPU rato) x (FSB : DRAM ratio)) [

Memory Frequency = (290 x (7)) / ] ((7) x (6/5)) [

Work this bit out first
] ((7) x (6/5)) [

6/5 = 1.2

and that becomes
] (7) x (1.2) [

7 x 1.2 = 8.4

Now remember the ceiling function, ][

]8.4[ = 9

Put that back into the main formula

Memory Frequency = (290 x (7)) / 9

So
Memory Frequency = (290 x 7) / 9
= 225.5Mhz.


Here is a great little program made by goddh0r called "A64MemFreq 1.1".. With this program you just enter your multi,mem divider,htt and it will tell you what speed your ram is running at without having to do all of the above..

A64MemFreq 1.1