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

[IanB]

With a 45nm CPU the GTLs are negative so when talking higher and lower values then mathematically that means closer to zero or positive values for higher and for lower values a more negative value is needed ??!!.

If something is controlled by a formula then it beats me as to why the bios cannot calculate this. I have a 45nm CPU so my GTLs should be negative which is partly backed up by my bios having increments of 5 in the negative range and increments of 10 in the positive range. Is that intentional or just luck ?.

I use a VTT of 1.4v so my CPU GTL should be -45mv.

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.