It won't damage anything, but it will cause instability. After lowering the speed through the BIOS, you should run something like Prime95 to see if you have any crashes occur.
Its really going to depend on what sort of issues you were having and what were presenting. This might be a symptom that is unrelated to memory timings, but you have started in the right place. Another thing to check is the volage of your memory. 1.5v is just about universal for Intel mobos.
Sony Zeiss 55/1.8 SSM, 24-70/4 SSM
Minolta 17-35/2.8-4 D, 35-105/3.5-4.5, 100-300 APO