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Old 01-09-2010, 08:33 PM   #1
Offler
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Join Date: Nov 18 2009
Location: Bratislava
Posts: 278
Post DDR 3 Settings on DFI boards

So many of users were very desperate when trying to tune their X48-T3RS to work fine.

Common issues with these boards were:
- random BSOD
- random crashing
- failing random stress tests

Most weakest part of this board was indentified by some users as the Clock generator, but in fact the real problem is with DDR3 memory controller hub and of course the amount of possible settings in the Bios.

I did cross testing between Nanya Elixir and the OCZ. If trying to run the memory on 1600Mhz the system might be unstable. For first time i thought that the OCZs are damaged, but later i applied same method of tuning I found for Nanyas.

Before starting you need to know some things:
a) the intel reccomends for x48 at1600Mhz 1.9v, however such high voltage can cause memory with lower voltage to cause malfunction.
b) x48 can work with 1,5v on 1600 if memory works.

And to tunning

1. Set the board to default FSB (400Mhz)
2. Set the memoru to 800Mhz for the first time (or other frequency lower than 1600)
3. Test the CPU to be completely sure that voltages are good set and cooling works properly.
4. When done there is good time to test the memory

Set memory to 1600 Mhz and default voltage (+ 0,03v more)

All other memory values set to Default EXCEPT:

and now the hard part

DRAM CLK Driving Strength: Level X
DRAM DATA Driving Strength: Level X
Ch1 DLL Default Skew Model: Model 0
Ch2 DLL Default Skew Model: Model 0


DLL default skew model will be same for both channels (if using same DIMMs of course).

"CLK Driving strengh" value cant be higher as "DATA Driving Strenght" - else system will not boot.

How to set DLL default Skew model?

DFI reccomends various settings for various chips. Different for Micron, different for Elpida and so on. If you don have these values available, just set "Data driving strenght" and "CLK driving strengh" both to 4.

Then Set DLL default Skew model to Mode 0 (both channels of course) and try to boot. Restart the computer, set it to Mode 1 and repeat.

Some of the settings will work better, some worse. Note those where you was able to boot the system.

What does CLK Driving Strength/DATA Driving Strength exactly do?

As written they represent some sort of strenght of communication between chipset and memory chips. If you did previous test on 1/1 you can only set those values stronger, but you cannot adjust them to weaker values, this can make your testing unusable.

When you re-test the DLL default skew modes with 4/4 or 3/3 you can still change the values both higher and lower.

I have my DLL default skew modes. What now?

System should be bit unstable right now. There are slight signs that you are going good or bad direction. First keep "CLK Driving Strength" at 4 and try to set "DATA Driving strenght" to higher values. Once you cant boot, or reboot your system the value is too high, and try to set it to lower value, until some of the problems are solved.

Now you just have to play around with the driving strenghts on those modes, where the computer was able to boot. After some time you will find your settings.


This can be applied to any DFI board which allows to set DLL Default Skew modes and Driving strenghts, just check how exactly the chipset works with voltage.

This part is really hard. You must be able to detect where the system is at same level of stability, and where it loses the stabillity. Of course the best value is in the middle.

Same testing is also good for CLK driving strengh when you found your Data Driving strengh. just remember that those values have to be same or lower.
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