@Nick@crete: You cannot make custom divider just like that. AMD has integrated memory controller and memory speed is obtained by dividing CPU speed with some integer value. That integer value is controlled via memclk frequency bits ( originally only 2 bits thus 4 dividers available - 200,166,133 and 100). But there is another undocumented bit so with 3 bits you can have 8 dividers: 200,183,166,150,143,133,120,100). Newer revisions have one more bit (or maybe 2?) but only couple of them are known (217,233,250).

Please try calculator and see what happens when your CPU is not overclocked, try to use various dividers (memory clock). Remeber, memory divider is integer value and memory clock is target memory speed (of nonoverclocked system!). By dividing CPU speed with memory divider you should have memory speed less or equal (never greater than!) target memory speed. When you overclock your sistem, divider remains unchanged but since CPU speed changes so does memory speed.

Example:

1) stock CPU , Opteron 175 , 2200MHz (11x200)

If you want to run your memory at 200MHz, so you chose 200 divider which gived 11 memory divider so 2200 / 11 = 200Mhz.

But you cannot run it at 175MHz! If you choose 180 (which is actualy 183.333) , memory divider is 12, so 2200 / 12 gives 183.33MHz, it is greater than 175MHz. Ok, so you chose 166 divider which gives 14 memory divider and memory runs at 157MHz (it is not even 166MHz).

For 175MHz you need 12.57 memory divider. You see that is not integer value.
Try to play with calculator and see what happens.