Overclock E8500 to 4Ghz with P5Q PRO Turbo and 1066Mhz RAM

IMO I leave FSB Strap on AUTO, set the Ram Divider for final speed afte setting FSB speed.
I used to run my C0 e8500 @ 4.0GHz both on 9.5x444 and 9.0x500 quite easily. It needed 1.29v (load).

Make sure you turned on Load Line Calibration if there is too much vdrop present, I don't generally disable the power saving stuff like c1e, speedstep, imo doesn't hurt to save a little bit of power and keep temps a tad lower when not under load.

I would guess that chip needs 1.25-1.40v, but you didn't BSOD you just froze that's kind of a good sign sorta...What settings are you running your RAM at?
From what I found you need to run 5-5-5-15 timings and 2.1v @ 1066.

What did you set for other voltages for the board itself? I ran 1.26v on NB/FSB. It's been a long time now, but it'd defnately help to know what other settings you have or haven't changed in that section of the bios, and it could show the reason why you are locking up.

What does the voltage show under load while stressing with prime? (cpu-z, everest, hwmon, etc). If you don't have Load Line Calibration enabled, under load your chip is probably loading at under 1.30v or so...maybe needing a bump up one or two steps in voltage.

Keep us posted, and to me it seems like you're fairly close, just need some fine tuning to dish out that stability.

I would really recommend removing some other voltages off of auto, just for the sake that they might be using too much voltage at that level. I would also recommend you set the ram voltage to spec, if specs call for 2.1v at 1066, definately do so, if you're at 1000, 2.0v will be fine, hell 2.0v might be fine at 1066, but 1.8v at that level might cause issues/lockups/bsod's. Also are you running Prime in small FFT's for CPU stress or Blend for system stress? I'll do a run of both. Also if you want a good 1 hour test, try OCCT.

I usually ran my NB and FSB at 1.26v, VTT at 1.54v, sb/pci-e set to 1.20v (min value), etc. That way auto is not cranking them up and heating up components that don't necessarily need to be for an overclock. Glad you got it going at 4ghz though. Keep us posted!