Laptop Memory Question

[Jay Flows]

First off, I want to say thanks to anyone in advance that can offer me advice on memory.

I have a laptop that runs very slow because it only has 2gb of memory. It's my wife's laptop which is a problem because it's a Japanese OS that is running on Windows 7, so can't change the OS to english and then back. I ran Crucial memory test and it came back with some compatible memory of :
2GB DDR3 PC3-12800 and
8GB (4GBx2) DDR3 PC3-12800

I personally own 4GB (2GB x2) DDR3 PC3-10600 from when I upgraded a laptop earlier. What I'd like to know is if I test it out on the laptop and it doesn't work, will it do anything bad?
I'm pretty sure it won't work, but I'm thinking of giving it a try before I go out and fork over 60-70 bucks as I have to pay tarrifs for living in Japan, it's kinda of annoying, but I like Crucial memory and memory out here isn't exactly cheap either.

In fact, I bought an MX100 SSD, and 8GB (4GBx2) DDR3 for like 10 dollars less even with tarrifs taxes applied compared to what was offered out in town. So sometimes you win some on imports and most of the times you don't.

 

[RageGamingZone]

I think they should work even if they are not showing the same speed rating. No this will not break anything or do anything bad to the computer and it is worth the try.