Two Questions about DRAM Drive Strength

[felinusz]

Sometimes called driving strength. This feature allows you to control the memory data bus' signal strength. Increasing the drive strength of the memory bus can increase stability during overclocking. DRAM drive strength refers to the signal strength of the memory data line. A higher number means a stronger signal and is generally recommended for an overclocked module to improve stability.

http://www.dfi-street.com/forum/show...t=11397&page=1




I'm wondering specifically which active DDR voltage signal DRAM Drive Strength refers to? I wonder, because a high/low DDR VDIMM voltage should have a signifigant influence on this setting, shouldn't it?

Next question - specifically what adjustment do various DRAM Drive Strength values make to the voltage signal? "Level 1" through "Level 7" doesn't tell us much.

A "Stronger Signal" implies to me either a higher voltage, for better signal switching from VSS to VDD, or a voltage signal that is manipulated in some manner.

[Ubermann]

This is something i want to know also.
No fun with stuff you have no idea what it is.

[EMC2]

http://www.dfi-street.com/forum/show...t=11397&page=1

I'm wondering specifically which active DDR voltage signal DRAM Drive Strength refers to? I wonder, because a high/low DDR VDIMM voltage should have a signifigant influence on this setting, shouldn't it?

Next question - specifically what adjustment do various DRAM Drive Strength values make to the voltage signal? "Level 1" through "Level 7" doesn't tell us much.

A "Stronger Signal" implies to me either a higher voltage, for better signal switching from VSS to VDD, or a voltage signal that is manipulated in some manner.

There are two drive strengths... what are typically called DRAM Drive Strength (or sometimes simply Drive Strength ) and Data Drive Strength.

They control the drive strength of two seperate groups of signals to/from the memory.

Drive strength itself has nothing to do per say with the actual voltage levels of the signals. What it controls is the slew rate of the signals - i.e. how much current is available to drive the signals from one state to the other (high-to-low or low-to-high).

Too weak of a drive strength limits your max OC because it takes longer for the signals to transition (change) from one state to another.

Too strong of a drive strength can cause ringing and signal reflections, which means it will take longer before the signals stabilize after a transition, which again limits your max OC.

There are also other factors that come into play (like termination resistor values, the structure of the output drivers in the memory chips, etc.) that determine the best drive strength for a particular setup.

In regards to what the numbers indicate in regards to slewrates - varies by MB... but for the DFI nF4, Bigtoe's info in the thread you linked tells you the answer in regards to which numbers are stronger and which are weaker drive strengths.

Peace

[felinusz]

Thanks man, that's exactly the explanation that I needed

Cheers