Setting GTL refs

[mike gunnz]

Been messing with my QX9650 picked off the MM and its proving a thirsty overclocker. I need to put 1.45v through the CPU core for an overclock of just 4GHz (400 x 10) and 1.47v on the FSB. My motherboard is fully water cooled so I'm not unduly worried about these high voltages in the short term.

Ive read up on GTL's over on XS forums and have followed the formula (Vtt x 0.667 + Y = Vtt x 0.635) to get an accurate GTL figure of -50 mv. So far so good.

My question is this, given that my motherboard allows me to set four GTL refs independently do I need to set them all to -50 mv? I currently have GTL 0 & 2 set to -50 mv and GTL 1 & 3 on Auto and its been stable for almost 3 hours. But setting all four GTLs to -50 mv gives instability.

Why is this?

 

[Greebo]

Since every different CPU has a different GTL Ref preference and then every FSB in generally also has a different GTL Ref preference. So there's no right or wrong value I would assume that there is differences between cores in cpus as well.

You can only use the rough calculation method to get a staring point for GTL, nothing for it but change in bios, test, reboot, repeat until you find which works the best for your cpu.