Just a bad Chip?

Hi all, just wondering if anyone might know what my problem is with o/c.

Currently I have

e6300 @ 475*6
FSB at 1900
vcore 1.425
mem @ 5-5-5-15 @ 2.1v @ 1:1 950
N/B at 1.5
P5B-E

Lapped CPU and Heatsink, with correct thermal paste quantity and correct seating.

Now clearly my board and memory can handle the overclock as this setup runs quite stable.

The problem I have is when I try and set my multiplier to 7 I just can't get past 410 FSB, even if I crank up the vcore to 1.5 (not sustainable for me due to temps) I can't do it, the comp just shuts down after a few minutes of TaT, and when I say the temps get high, they are only 68 or so, not even normal shutdown speeds.

This is really annoying me, and I'm just wondering if anyone has any suggestions regarding this.

The only thing I can think of is I got a bad chip that needs too high a voltage for overclocking and that the vdroop on the board (.07 @ load) is just too much for it.

Just for reference, my temps are

With Asus Probe temps.

e6300 @ 266*7 @ 1.275
Case 33
CPU @ Idle = 31
CPU @ Load = 44 with TaT
CPU @ Load = 43 with Orthos (CPU stress only)

TaT Temps
CPU @ Idle = 31
CPU @ Load = 46/43 with TaT
CPU @ Load = 42/38 with Orthos (CPU stress only)

----------------------------------------------------
e6300 @ 400 * 7 (2800)
vcore 1.4
mem 2.1
----------------------------------------------------
TaT Temps
CPU @ Idle = 41/37
CPU @ Load = 62/58 with TaT
CPU @ Load = 55/53 with Orthos (CPU stress only)