Quote Originally Posted by dexx
How do we know that the memory refresh rate is 7.8ns (or whatever)?
Isnt this just the value which would apply if you are running your sticks at SPD (eg 200MHz 2.5-3-3-8)? Would this value vary depending on your MHz and timings?
The needed (approximate) refresh rate depends on the chips themselves. It is determined by how many rows are in the chips... easiest way to tell (other than data sheets) is to set the timings to "default" and look in the advanced settings of memtest to see what it's set to (advanced timings option of memtest)... or use everest, sandra, etc. and see what it says in the SPD.

The refresh rate should stay the same regardless of the frequency you are running at (for example 15.6uS no matter what). Too high a refresh rate causes the chips to use more power, get hotter and thus slow down, and also generate more noise limiting your FSB. Too slow a refresh rate and data can be "forgotten" by the chips (it gets corrupted actually).

Quote Originally Posted by astaris
Maybe Tref is derived not from the memory clock, but from the cpu clock?
Why else would they have dif reg settings with the same MemClock count. There are distinct patterns in the reg settings too

Peace