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Memory tweaking - DS & SR

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Little help guys,


I'll bring you all up to speed by posting the PMs I've sent/recieved from uwackme.



Hi uwakme,


What do you think of the memory settings I'm using at the moment?


Any suggestions of how to start working on the slew and driving settings, everytime I've tried playing with them they mess everything up.


Any ideas what their default settings are or what would be some safe settings to start playing with?


Those are pretty fast alphas.


For testing higher you might want to drop back to 5,4,6,3,3,4,5.


Then, I assume your have SR DS on auto, just pick like 240Mhz, then set them to DS 6 SR 7 and start upping the FSB til it errors. Then at that point, raise/lower each DS and SR to see the effect of doing so. This is the only way you can gauge the impact.


Also, before changing, use WCPREDIT to look uop what the "auto" setting is giving you for timings.


bus0 dev0 func4...... offsets:


DIMM1 DS 7D, 81 and SR 7C

DIMM2 DS 67,73 and SR 66

DIMM3 DS 65,71 and SR 64


Look up numbers in those offsets, they = the number you enter in bios... 0-15 is 0-FF.


Hope that helps.


Thanks uwackme,


I've checked it out in the hex editor and it comes back with these values,


DS 44, 44 SR BB


for all 3 Dimm slots what is the relationship to the decimal values set in the bios? Surely 1 - 15 in hex is just 01 - 0E


I'm a little confused

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Thank you uwackme


Those numbers mean literally... DS of "4" and SR of "11" as if you set it to that in bios.


So go change them now to 4 and 11 and you should see no change.


the "SKEW" in this is not from DIMM1 to DIMM2..... it is instead a SKEW of when data is ready from the DIMM vs the clock -edge of the memory clock.


The number should be just about the same for all DIMMs, at most maybe off by 1 or 2. So dont bother experimenting with SR 8 on DIMM1 and SR 15 on DIMM3, that aint gonna go well ;-)


But on mine, 2x 512M is best at DS 6 SR 7, while on NF7-S with ONE 512M stick, DS1, SR2 is best. NF7-S "auto" for most bios's is DS 3 SR 10 but the D10 bios's are DS 2 SR 10.


This is one of those... my advice wont help situations. This is where a TON of experimentation and testing can help find a few more FSB at most.


Key thing is to get the memory on the hairy edge, so the effect of changing DS or SR is a noticable act, and then gauge how it affects the memory.



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Do these rates actually have an affect on total system latency or memory bandwidth, or just fsb potential. Any chance changing them from auto to what they should be, then tweaking will get me to the covetted 258fsb 4gb/sec.


edit: nm the vdimm mod got me 4gb/sec w00t!.

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