Hi CryptiK,

Thanks for the reply. I was trying fifferent values last night when running HyperPi but had failures on cores 1 & 2 when counting 0-3. I will have more time tonight so will disable die 1 and aim for stability on a die by die basis. I have heard people using prime and then determining whether to raise or lower the GTL ref by the amount that it fails - any more info on this or a similar method would be greatfully recieved.

It sounds like I need to find the 0.635 offset value in my bios and also which GTLs refer to the 0.667 multiplier.

I have read the article at thetechrepository and their diagram of which GTL does what differs from your explanation:-
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I think this is fairly important as I understand that values for data bus are generally higher than those of the address bus.