At worst, you'll fry the RAM. However, I do believe that most RAM manufacturers have "limited lifetime warranty". I fried my Kingston DDR2 value ram once by overclocking and overvolting and they (Kingston service centre) voluntarily changed for me. But of course, I'm not suggesting you to do the same. Like what Maziar mentioned, keep it at 1.65
The RAM frying is not my concern, it is supposed to be able to cope with up to 2.0v, and if it did fry I can easily replace. My issue is the CPU chipset dislikes having more than 1.65v which means I am afraid of damaging my i5 750.
I just wonder if 1.7 will actually damage my CPU or if it will just reduce its lifespan a bit (like OCing does) which does not concern me so much as I don't keep my computer for more than 3 years.
Have been using 1.7v for a few weeks and I certainly have no issues, but that does not mean behind the scenes the CPU isn't getting frazzled bit by bit.