NF7-S Rev.2 + overclocked graphics

Just got this board . Think its great i tried 200*11.5 and got it no problems but when i overclock me Geforce3Ti200 it crashes out of 3dMark 2001 .When i lower the fsb to 193*12 and overclock me graphics card i get no problems . I tried upping me agp voltage to 1.8V which helps a bit but it still isn't 100% stable with high fsb and overclocked graphics card .
Has anybody had any similar problems or any solution.

Thanks