Official MSI P7N Diamond (780i) Discussion/Review/Overclock/Guide/BIOS Thread

[Overspeed]

New high hit on the E8400. 3.51Ghz using these values:

BIOS: 1B4
FSB: 1560
RAM: 780
VCORE: +0.2v
DIMM: 2.1v
NB: 1.35v
SB: 1.6v
FSBT: 60

Stability unverified, but so far so good.

Edit: Above values refined after experimenting, still able to achieve 3.51Ghz:

BIOS: 1B4
FSB: 1560
RAM: 780
VCORE: +0.15v
DIMM: 2.1v
NB: 1.35v
SB: auto
FSBT: auto

I'm not sure what role the FSBT plays but I was able to get here with it left on auto. SB modification also seemed to be redundant. System would only become stable when NB voltage bumped up. 1.2v = fail 1.25v = fail 1.3v = OS load but not stable 1.35v = stable sweet spot. I'm also noticing that the vcore can remain relatively low ... at least at my current best of 3.51Ghz. More to follow.

[theYipster]

Overspeed,

I've asked MSI for a detailed explanation of all BIOS voltage settings. With this information we can shed a bit more light on the OC possibilities of this board.

However, it looks like the new BIOS is doing the trick for you. Two things to keep in mind:

On the reference 780i boards, 1.4v is often needed on the NB to achieve stability between 3.6-4.0ghz. Furthermore, I believe the reference boards default NB voltage to a higher value -- 1.3 or 1.35. Considering that the P7N uses the same NB, I would expect similar voltages are necessary to achieve stability. Try a NB in the range of 1.4-1.45 and see if that can't get you stable at 3.6ghz, let alone 4.0v.

As for your vCore, the consensus on a maximum voltage limit for OC'd 8400s is 1.45v. Unfortunately, thanks to the P7N's unique way of setting vCore, it's not necessarily easy to tell when you've set 1.45v in the BIOS. To do this, you need to know your chips VID. With Speedstep disabled, open (or first download if need be) Core Temp in Windows and read the number for VID. To get the actual voltage set via vCore in the BIOS, simply add the BIOS vCore to your VID. Note that the voltage you set in the BIOS will be higher than the voltage supplied to your chip while idling in Windows, thanks to vOffset, and that the voltage will further drop under load, thanks to vDroop. Your chip, however, should reach 4.0ghz on less than 1.45v, provided it's not a dud.

Also, what is the batch of your E8400? Many can do 4.0ghz on air as easily as a Q6600 G0 can do 3.6ghz. I had one (a Q746A) I sold which apparently can bench 4.5ghz on air on an evga 680i, but it does need a bit of voltage to get there.