I just got a new MB/CPU and want to do a clean install of my OS. Currently I have two partitions on my HD, one for the OS and one for all my data. Can I just format the OS partition and do a clean install on that partition of the new OS? I just don't want to lose all my data files. I have most backed up, but would take the entire day to backup the rest probably.
More aboutreinstall existing partition
You will probably be all right doing that but it is always best to backup anything important before re-installing an operating system. When you run the installation choose the partition you want the os on and delete the partition. Then create a new one and let windows install there. Good luck.
...Can I just format the OS partition and do a clean install on that partition of the new OS?...
YES, during the Windows installation as mentioned... you WILL have to re-install all programs and games of course