Possible memory problem?

Yes

How do you suppose nocheese?!? if 1200mhz is OCn the mobo it wont like 1600mhz very well. Thats 400mhz more OC than they even say is supported. I wouldn't think it is. It would work but would underclock to 1066mhz. You could let it go down and tighten timings.

So it will sort of work. No because it wont go at its standard speed but yes because it will work at a lowered speed. Good Luck!!!

No, it won't run at it's (the memories) optimal speed. But it will work (answering if it is compatible) and the OP can move it to a newer computer in the future (if compatible). It will run no slower than the exact memory that motherboard takes so nothing is lost by using the higher speed memory.