i dont see a difference between 1183 mhz and 888 mhz what its suppost to do ?
This is a tough thing to answer...
you may get more running the ram over 800mhz however i have read articles saying that any extra MHZ above the FSB (400x2 in your case so 800) will be simply wasted as the memory is waiting on the FSB..
Is it faster @ 1183? To be perfectly frank… im not sure. Personally I would clock the ram down to 800 and make the timing tighter to CL4 is possible.
Someone else will have to answer your Memory MHZ question.