Athlon 64 3000 oc?Help!

I've been OC'ing my new Athlon 64 3000, doing small bumps slowly since it's my first OC.
I've been using the Easy Tune 4 software that came with the mobo.
The stock speed is 2.0ghz.
My inital numbers were: 3DMark2001-18,989
PCMark2002- cpu 6526
Mem 8044
HDD 1947

The best I can OC to is 2.249ghz by upping FSB to 225, with vcore @1.525 (stock).
These were the last results: 3DMArk2001-21,314
PCMark2002-CPU 7335
Mem 9094
HDD 1877
Anything over this FSB and the system crashes.
I tried increasing the vcore to 1.550, same result.It seems like any increase to the vcore causes a crash.
I went into BIOS and tried to manually OC, still crashed at anything over 225fsb/2.2499ghz.

What is the next step to increase my clock speed and stay stable?
Should I try more v-core?
Is there a "safety" that shutsdown system if vcore is too high, and can it be disabled?
Temperature has never been over 40c even under load.
(I believe the multiplier is locked on this set, but if I'm wrong please let me know.
Thanks!

How-to Overclocking Athlon64

This might help...

Don't use EasyTune. It does some real strange things. Use ClockGen. From here, you can change the multiplier below the stock of 10x. Set the vcore to 1.7v in the BIOS, and set the CPU Overclock to 201. However, you probably won't be able to get too far without a PCI 66 ATA controller, as you'll get HD corruption beyond around 240 due to the unlocked PCI bus.

What are you running for LDT speed? Default on a nforce3 150 board is 3x (600mhz), but if you are running 225 HTT at 3x then you are at 675mhz which might be to much and thus causing the crashing. Try and drop your LDT to 2.5x if you have the option in bios. You will also need more voltage to your cpu. I'll list some of my settings I've successfully run with stability. I run 245x10 normally though as it appears to be my sweet spot.

Vcore: 1.68v (1.7 in bios)
Dvimm: 2.9v
LDT voltage: 1.4v
LDT Speed: 2.5x
Ram timings: 2-3-3-6
Memory divider: 5:6
Multipler: 9.5 or 9(using clockgen)
HTT: 245 in bios then 260 with 9.5 multi using clockgen