Replacing motherboard+CPU, will I need to format HDD?

[Orbit Storm]

I'm already aware that replacing the motherboard will require me to reinstall Windows 10 but does that also require a complete wipe of my hard drive?

This was a prebuilt system that came with Win8 that I've since upgraded to Win10 via the free upgrade and have already confirmed with Microsoft support that I won't need to buy a new key but the tech claims I'll need to format my drive and all data will be lost.

However, I've seen threads here on Tom's that claim that's not true and by selecting "upgrade" when prompted to reinstall, I can avoid losing data. I've also seen threads that claim the opposite.

In short, I can't seem to find a definitive answer on this: will I lose all data on my drive by reinstalling Windows after replacing my motherboard?

 

[Lutfij]

Yes, reinstall your OS after a motherboard change. Not a complete wipe, only format the drive off which your OS was on.

You should back up all your critical content on a removable storage device like a pen drive and then proceed to format=reinstall your OS, after you've created a bootable USB installer.

Often times the upgrade process doesn't go well and can cause the system to undergo a format/reinstall which is why we suggest you back up your data and then proceed with the re-installation. It also ensures that you don't loose time troubleshooting.

 

[Orbit Storm]

Problem is, my motherboard is dead, so I don't have any way to recover data that I don't want to lose, not without buying an additional hard drive.

I'm not even certain a new hard drive will be the answer either since I likely can't install my copy of Win10 on two drives.

 

[VJ_Gamer]

Problem is, my motherboard is dead, so I don't have any way to recover data that I don't want to lose, not without buying an additional hard drive.

I'm not even certain a new hard drive will be the answer either since I likely can't install my copy of Win10 on two drives.

Lutfij is right. You need to re install since its running with a different Motherboard and CPU.
Check the below links for more details:
http://www.tomshardware.com/answers/id-1739440/reinstall-windows-changing-motherboard.html
or
http://www.tomshardware.com/answers/id-2813884/motherboard-reinstall-windows.html

Good Luck. Peace.