Formatting computer, questions

Hey guys me again...

so blue screen problem is still happening so I'm thinking of just getting the laptop and formatting it.
What I don't know is that since there is no external hard drive handy and with almost half a terabyte of data I don't know if I should do it since I can't back it up.
The laptop has a hybrid drive with 2 partitions, one 30 Gb for the OS (Windows 8.1) and another 800 something for storage. If I format it and install the OS to the 30Gb partition will it erase the data on the 800 one?

Thanks

If you configure the format process correctly, the data should be fine. It always a risk that something goes wrong as every time you play with the hard disk but normally it should be fine. Just make sure you do not leave the installer do things automatically so that you can be sure it will not change the partitioning and chooses the right one to install windows on.

Thanks man, I wasn't sure what would happen and since I've never used windows 8.1 and it's my girlfriend's laptop I wanted to be 100% sure before doing anything.