I have a question Mikey. From what I have read, increasing Vref is required when the low level input signal crosses VIL (max) and as such this increases VIL (max) and prevents the input signal crossing it as it remains in the valid VIL range. If we raise Vref too far, it creates the problem that the high level input may cross VIH (min). My question is can this situation (the crossing of VIH (min)) be corrected by raising Vtt? What relationship does Vtt have with Vcc and Vref in terms of it's ability to aid stability and how does it relate to VIH (min) and VIL (max)? In essence, how does increased Vtt really aid stability? I have read a bit about this but I'd just like your opinion on it.
I ask as I have not been able to achieve much by playing with my GTL's other than getting 4005 MHz stable at one notch lower vcore than was previously required. However if I raise the speed to 4050 MHz, I have found it impossible to get it stable using the same vcore as 4005 MHz, and that raising Vtt above 1.16v, even when adjusting the GTL's to compensate to give the same output ref voltage (eg: ~0.8004v) causes the system to become less stable, and rather than erroring in Linpack, it will either just reboot or bluescreen. I'm just trying to understand the reasons for this situation.
I think I have proven what I thought to be true, in that adjustment of GTL's will not net much of a significant gain in stable FSB or overall CPU clock, but can provide a final stability to an almost totally stable clock, or in my case, allow slight lowering of vcore for a given stable clock speed.
@PolRoger - no problem at all, I just saw a lack of any mainstream discussion of this issue and simply shared what little I knew. Mikey's knowledge of electrical engineering relating to processor/motherboard function dwarfs mine, however, and I in turn am glad people with his knowledge base have contributed also.
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