Please help OC 3570k at 4.0

I've just started to learn about OC and would like to know your opinion on my first attempt.


intel i5 3570k
ASUS P8z77 V LK - http://www.asus.com/Motherboard/P8Z77V_LK/
Gammaxx 300 air cooler - http://www.deepcool-us.com/Product/GAMMAXX300/
Palit GTX 670 Jetstream
Corsair Vengeance 1600Mhz 2x4GB 9-9-9-24
Corsait GS600 PSU
Cooler Master HAF912, 2 front in, 1 side in, 1 rear out


OC profile1:
ai overclock tuner - X.M.P 1600
turbo ratio - manual 40
bclk - 100
cpu voltage 1.032V with offset auto
cpu fixed frequency - 250
cpu power phase control - standard
cpu power duty control - t.probe
cpu current capability - 100%
cpu load line calibration - auto
enhanced intel speedstep - enabled
turbo mode - enabled
others - auto

Using prime95 blend 2hrs (no errors):
vcore max - 1.16
VID - 1.2109
CPU load max core temp - 73C
CPU idle/(low usage) max core temp - 47C
CPUTIN max - 90C
cpu power - 61 watts
tdp - 77watts
GPU - idle, not stress tested, 34C

Using prime95 in place large fft - error less than 1min:

I've read that 4.0 does not require too much voltage.
If I get error in Prime do you think this voltage is still low?
Should I use manual without offset?

Thanks