help, strange divider issues A8n32

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hey,

I am having trouble setting the divider to manual. I use 8.5x340 = 2.9ghz, I set the mem divider to auto and pc boots fine, i get into windows and cpu-z reports mem is running at 220mhz. Therefore auto is selecting the 133 (2:3) divider to keep the mem as close as it can to its rated speed. However if i select the 2:3 divider mnually the pc refuses to boot :/ I have no idea why. I also set the mem divider manually to 1:2 and tried various fsb frequencies too se how high I could go but again it didnt want to boot when I tried 340 with that divider either, it seems my mobo dosent like a manual divider being set at high fsb speeds any ideas?

 

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Opty 146, ram is rated is PC3200, any particular reason .5's shouldnt b run? Mem spec shouldnt matter as I at 340 with mem divider of 100 (1:2) my mem should be running at 170mhz, well below it capable speed. I have tried using a 6x divider with 340 fsb and 1:2 divider but no post, i change to auto mem settings and it posts :/