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Ideal Tref - Try this


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Hey guys,

 

There's some discussions over at XS about Tref and one pointed back here explaining the relationship between Tref, memory clock and refresh time.

 

I made a small excel spreadsheet which needs testing. Just input your memory stick size and memory speed in Mhz and it should give you the theoretical ideal Tref:

 

http://homepage.ntlworld.com/james.waynewright/Tref.xls

 

Let me know how it goes.

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Hey guys,

 

There's some discussions over at XS about Tref and one pointed back here explaining the relationship between Tref, memory clock and refresh time.

 

I made a small excel spreadsheet which needs testing. Just input your memory stick size and memory speed in Mhz and it should give you the theoretical ideal Tref:

 

http://homepage.ntlworld.com/james.waynewright/Tref.xls

 

Let me know how it goes.

 

Think there would be any difference between the NF3 and the NF4 for your formula??? Either way I'll try it when I get home tonight...

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Jimbo,

 

The numbers you get for 512MB sticks are suprisingly close to how I calculate Tref

 

Your formula = (4/MEM)/(1/FSB)*1000. How was this arrived at and does the XS thread mention anything about refresh rate for particular sticks. The formula that has been discussed on this forum is REFRESH/(1/FSB). Many sticks have and SPD refresh rate of 7.8us so the math with yours worked out for sticks of 512MB @ 200 are (4/512)/(1/200)=1563, the formula I am using taking into account refresh is 7.8/(1/200)=1560, but if the RAM was built to refresh significantly faster, let's say 3.9us then you still come up with 1563 and my results show it should be 780.

 

Just curious.

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Sorry, so far I've just assumed for a 128Mbit stick (256MB) that it has a default refresh of 15.6 us.

 

For a 256Mbit stick (512MB), 7.8us.

 

etc etc.

 

If you can improve the formula, please do!

 

I've changed the spreadsheet so you can input your refresh period if you know it.

 

Download it again and take a look.

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Sorry, so far I've just assumed for a 128Mbit stick (256MB) that it has a default refresh of 15.6 us.

 

For a 256Mbit stick (512MB), 7.8us.

 

etc etc.

 

If you can improve the formula, please do!

 

I've changed the spreadsheet so you can input your refresh period if you know it.

 

Download it again and take a look.

 

Keep tinkering and by the time I get home tonight you'll have the magical mystery tref formula that lets me run both my sticks of memory at 300mhz 1:1 1T @ 2-2-2-5 timings :nod:

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We put speed of the memory, not the divider speed right?

 

ie for me: I am running 10 x260 with a 9/10 divider on my 512 sticks giving me 236 Makeithurtz on the memory. So according to your flux capacitor calculations, I should select the Tref value that is closest to 1843.75 without going under?

 

:)

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Hello,

 

Yes always use the Memory frequency.

Anything near 1843, a bit higher or lower.

 

I have registered in the XS forum, need to wait a bit before I can post.

I would like to know if it makes a difference.

:)

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