Originally Posted by RobRedbeard
Thanks, but honestly, I do know this. While, I was not expecting him to say his motherboard only gives him 1.375v and 1.5v steps with nothing in between (I would have returned it for a different board at this point), it's not uncommon for people to test/run vcores on the E8400 up to 1.6v. I know he has a quad, but I also know he has a water block. My point was to set the voltage on the CPU, at least temporarily, to a point where you absolutely know the CPU vcore is not the culprit. For a dual 45nm, 1.375v is not enough to make that claim in the 425-470 FSB range. The quads can't escape the fact that they are just two duals. However, the quads can't take as much voltage as the duals (which makes perfect sense when you think they have twice the heat generation surface in the same package).
This means your boards voltage regulators are inadequate. Just in terms of shear wattage the board has to supply to the NB and CPU those speeds make sense. I would expect measured vcores on failed boots above that point to show drooping in the CPU voltage and draw down on the FSB voltage.
If your FSB is at 1.5v already, and your cpu is <1.4 you should be able to achieve at least 425MHz FSB. Otherwise, I'm inclined to believe it's a power issue. CPU GTL is something you'll need to adjust, especially with a quad, but there is no right answer. I'd say put your voltages at 1.375 and 1.5v (fsb). Then experiment with GTL, it's different for each CPU.
This might help:
Adjusting [Advanced] Gunning Transceiver Logic (A/GTL+) Voltage Levels
for Increased Front Side Bus (FSB) Signaling Margins and Overclocking
At the very least great information from you guys (not that I understand it all but I'm trying)! Unfortunatly, returning the board (bought it on the net in Germany) isn't really an option.
Now about theat GTL: this definitely makes sence but I don't have it in my BIOS, not under that name anyway ... could this be the CPU reference voltage in my BIOS?
Just for the record, my BIOS parameters are:
CPU Voltage (obvious what it is but what's a 'safe' limit' for dual or quad and what's the biggest effect of upping it, besides heat and reduced lifetime?)
Memory Voltage (obvious what this does as well, but limits and effects?)
FSB Terminator Voltage (not clear at all, I suppose this is the VTT but what does it do?)
NB Voltage (clear, just what are 'safe' limits or normally used values when OC'ing)
SB Voltage (clear, just what are 'safe' limits or normally used values when OC'ing)
CPU Reference Voltage (not clear at all)
Memory Reference Voltage (not clear at all)