What's a safe max voltage for the Northbridge? (any recent ish mbrds)

[Assimilator1]

Possibly asking 'how long's a bit of string?' but hopefully it's not asking the un-answerably!

Anyway I have an MSI P6N Platinium (Nvidia 650),& on a quick test (1.5hrs) it is stable upto 406MHz with the Northbridge @ 1.35v (proper testing coming latter).
At 412MHz it locks up ,though it could be the CPU (E6420) needing more vcore I wanted to try more voltage to the NB 1st as that has worked on previous FSB increases where it had locked up.
However 1.35v is already 8% over def ,so I lost my bottle to go any higher .
I have a fan mounted over the NB HS ,& my laser thermometer is showing just 42C on it when running Orthos ,so temps are fine .
With CPUs I know where I am as I have a rough rule of thumb of an absolute max extra vcore of 10% ,preferably & usually no more than 5-7% ,should I just use that same rule for mbrds or is it a different story?

Bearing in mind I will quite likely keep this mbrd for upto 3yrs (& want to sell it on in a working state afterwards) ,& that I run a Distributed Computing project 24/7 on this rig ,what's a safe voltage for the NB & how/why do you think that?

TIA

[edit] Altered the title slightly to widen the discussion.

 

[Shimmishim]

For 650... i'd say try to keep it under 1.55... that's what i ran my p5n32-e sli plus at... more than that and my board got unstable.

but to be uber safe.. i say stay at 1.45 to 1.5. i think your chipset should last a while at that voltage

 

[Assimilator1]

Ok thanks ,then going by that I'm well within safe limits atm ,though how can we know it's safe in the longer run?

Anyone else?

 

[Sylvanas]

What you are at now is fine, just make sure the temps stay that way

 

[Assimilator1]

Altered the title slightly to widen the discussion.
Also interested if anyone has run mbrds at 10% or more extra voltage for some time ,say 2yrs or more.

Inccidently I did bump my P6N up to 1.4v ,& a quick test seems to show its now stable at ~413MHz, but it won't go another 6MHz higher so I'm not sure it's really worth it for just another 50MHz on the CPU.