Probs with Tbird 1200/266

Hi

I'm having some troubles overclocking my Tbird 1200/266 AXIA.
It works fine at 10x133, but when i increase the FSB to 140, it won't post sometimes.
When it posts and i get into windows and can really torture the cpu without any lockups.
But when i reboot it won't post.
And the the procedure above repeats, some time it post sometimes it don't.

The same thing happens when i try 10,5x133.

Core Volt: 1.85
Cooling: Taisol Copper
Mobo Asus A7V133-C
Mem: 256 MB Mosel Vitelic (Can do 150 MHz2CAS2)
HDD: IBM 60GXP 40 GB
GFXCard: ASUS V7700 TV 32 MB

What is the problem, more core voltage or better cooling or maybe more I/0 Voltage?

Did you jump strait from 133 to 140FSB? try something in betwin. If it wont post maybe u can do the Vmod so u can get higher Vcore... what is the first char on the 3rd line? letter or number?