CPU voltages on Xeon

[SavellM]

So I have a Xeon X5650 2.66GHz.
I have it running on a Sabertooth x58 mobo.
I have overclocked it up to a nice 4GHz.
200x20 bclk, at 1.325volts core and 1.3qpi, rest is on auto.

I'm doing this as an every day clock as I only use this pc for gaming.

What do you think are safe voltages?
Or what line should I not cross?
Remember this is a server CPU.

Also it's running on a Corsair H80 and idles at 18c.
Prime95 (max heat setting) for 3 hours max 61c.

 

[SavellM]

It's actually 32nm

I was getting some weird issues at 1.3v flat with the odd bsod or random restarts.

At 1.325v it's all good.

So I can continue to try push the bclk on this voltage and see where I get.
Should I increase qpi voltage at the same time? Or how does that work?