GTL Ref Tweaking Guide

[saaya]

Ok im confused.

How do you know what GTL voltage you want in the first place? Other peoples settings? Black Magic/Voodoo?

Thats my exact question as well... I assume we just need trial and error and see which works best like any other voltage i guess?

yes, every cpu looks a slightly different GTL ref for each core, and every board varies slightly, so its a trial and error thing. but you can learn a lot from looking at other peoples results since all 45nm dualcore cpus are about the same, all 45nm quads are about the same etc

ill see if i can collect some settings from people to give you guys some more guidance.

but its called fine-tuning, if there would be a way to know what setting is best for your cpu, then the bios would configure this automatically and there wouldnt be a need to fine tune
btw, i dont think any other board allows this fine steps actually of only 0.007v
i remember my p5e3 had 4 options for cpu GTL, and it was applied for all 4 cores

Also, your spreadsheet says "enter current VTT setting or measured VTT in highlighted field" but you said that the vtt settings is +0.10v higher than the real vtt, so won't this affect the calculation?

sure, you gotta keep in mind that real vtt is lower than what it says in bios.
so if you set 1.2v in bios, enter 1.1 in the spreadsheet to see which GTL Ref ratio results in what GTL Ref voltage.

Basically this lets you guys adjust the FSB signal window.
you can increase the amplitude by increasing vtt, and you can adjust the center of the wave signal to compensate for the signal rising or falling too fast, at least thats how i understood GTL Ref so far

Well the attachment documents measuring points for reading the voltage with a multimeter, although I'm not sure what kind of heatsink you could use to actually take the measurement, as the points are right next to the cpu socket..

temps were actually quite ok as you can see

but yeah, joking aside, you need a slim heatsink like the TRUE or a waterblock. or you solder wires to it:


actually measuring gtl ref all the time doesnt make that much sense, every step is 7mv, so all you need to check is what the default voltages with your cpu and your board are at stock speeds with stock vtt and with increased vtt, and from that you know all you need to know already. so you can put a small heatsink on there just to meassure the voltages with a DMM and then after your done taking your notes, put the big heatsink back on there