Stubborn 4200+ X2

[Ubermouser]

I'm having a horrible time trying to get this poor thing to overclock. I can't get it to even a few fsb past stock and be stable (without hard rebooting) for more than a few minutes. If you could point out what I'm doing wrong, or what I should be doing differently, I'd be thankful.

This X2 4200+ Manchester Core is being cooled by a Scythe Infinity and a Silverstone FM121 120mm high-speed fan, controlled by Smartguardian. NB and SB cooling is passive, but I'm pretty confident in the P180b's ability to give more than enough airflow to the motherboard.
The settings I've tried for overclocking the core are:
11x, 10x, 9x, 8.5x, and 8x mult /w 1:1 and 6:5 ratio. I've also tried setting the CPU voltage to 1.400v, and the HTT to x3.

CPU: AMD Athlon 64 X2 4200+ Manchester @ 1.375v
Mobo: DFI RS-482 Infinity
Mem: 2x 1gb OCZ pc4000 EB - PE @ 1.65v
GPU: ATI X1900xtx @ stock
PSU: OCZ GameXStream 600w
Case: Antec P180b
Sound: SoundBlaster X-Fi Xtrememusic

CPUZ and temperature pictures:

(I can get the FSB of the board up to 314mhz at 5x mult, 1.35v proc, etc)

(This memory will clock up to 264mhz at 2.65 volts)

Idle Temperatures:

Load Temperatures:

(The CPU fan has no RPM sensor)
Ambient temperature is ~27c.

Again, if you can give me any advice on how I would go about overclocking this stubborn little dual core, that'd be great. Thanks in advance for your help!