My first E8400 (Q748A116) needed a lot more vCore for sigged 4.23GHz than others were reporting (1.45v), so I got another one to see what's going on.

The new chip (Q745A731) doesn't need as much vCore (only 1.40v) for the same OC, but it runs 10(c) hotter.

To confirm it wasn't the AS5 breaking-in, I remounted the first chip and it was still running 10(c) cooler.

Q748A116 @ 4.32 35 / 55 / 1.45v

Q745A731 @ 4.32 45 / 65 / 1.40v

Your opinions are appreciated:
1) Which chip should I keep?
2) Is it safe to go beyond 1.45v if the chip is running cooler?
3) Is it safe to go beyond 65(c) if the vCore is lower?