Overclocking 8K7A+

[roders]

I've got my 8K7A+ & AMD 1600 XP to 290FSB AMD 1800 XP (1.52 Ghz) simply by upping the FSB in the Bios to 145Mhz (from 133) I now want to change the multiplier, which I have done, but it has not affected my CPU speed at all, in fact I'm wondering if the Multiplier has been change at all.
Do I need to clear the Cmos (or something else) before the Bios realises I've changed the Multiplier?

[roders]

Damn, I tried clearing the CMOS, so I got my default Bios settings, but now the max fsb (set in Bios) I can get is 140.
Anything above this and after the inital Bios screen (showing CPU/FSB speed, drives etc) I get stange black screens with award or Flash and white lines on them (as if soem next stage of the Bios has tried to load but failed) I've set my multiplier to everything, 10.5 (which is the defualt for my chip I believe) auto, the lot, does not make any difference.
After my inital 145 overclock I was going to play with voltages for CPU ram etc, and up the mulitplier to overclock my CPU more or downl**** it so I can up my FSB in the BIOS, as my cooling seems fine (average temp was 109F with 145FSB/152Ghz).
I wonder whats going on?
p.S 145 was a stable overclock, 150 and things started crashing (orginaly).