Hi Zheng,

I believe that "-x GB" simply means that there are different Trfc values for each size module.

Trfc is stored in MTB units, though. So you need to:

1. Convert nCK to nanoseconds

2. Convert nanoseconds to MTB units

For example, if you have a 1Gb module that is running at 800MHz, then Trfc will be 88 clock cycles. 1sec / 800MHz = 1.25ns per cycle, therefore 88 cycles = 110ns.

Then you need to convert the total time into MTB units. So if your timebase (SPD bytes 10 and 11) is 0.125, Trfc is 110 / 0.125 = 880. (This matches the calculation shown for bytes 24 and 25 in the SPD spec: http://www.jedec.org/standards-documents/results/Annex%20K%20SPD).

On Fri, Apr 1, 2016 at 5:30 PM, Zheng Bao <fishbaoz@hotmail.com> wrote:

                            DDR3-1066 DDR3-1333 DDR3-1600   DDR3-1866      unit
                                 7-7-7           9-9-9        11-11-11     13-13-13
nRFC-1 Gb                  59               74               88               103             nCK
nRFC- 2 Gb     86              107            128 150              nCK
nRFC- 4 Gb    160             200    240               281              nCK
nRFC- 8 Gb    187             234            280               328              nCK

Hi, All,
Above text is extracted from the spec of a DDR3 chip.

I am trying to decide the Trfc.
What does "-x Gb" mean? How do I know which row in the table I should use?
Thanks.

Zheng

--
coreboot mailing list: coreboot@coreboot.org
https://www.coreboot.org/mailman/listinfo/coreboot