How to set up GTL Ref Values for 45nm & 65nm

[rob2k]

I think you have misunderstood. The GTL values are ratios of VCC or other voltages. In some/most BIOSes you can set the ratio (eg. 0.67 x voltage) directly and that gives an absolute (positive) value, always. In some other BIOSes you are not able to do this, the ratio is set and cannot be changed, so you must enter an OFFSET to change the ABSOLUTE value to what is required, eg.:

0.67 (fixed) x voltage +/- offset = GTL ref voltage

The OFFSET can be positive or negative, but the final ref GTL will always be a positive value. It depends on what your mobo BIOS allows you to change and if you must enter an offset you must know the fixed ratio that is being used.

Hi Ian,

I have used the formula from post 1 Vtt x 0.667 + Y = Vtt x 0.635 where Y = the GTL ref adjustment for a GTL ref V of between 0.8 and 1.0, my bios asked for GTL ref V in milli volts rather than asking for the multiplier so for a Vtt of 1.4 Y= -45mv. I think my bios is asking for the value of Y.