I installed a new SSD, and installed Windows 10 onto it.
After som quirks during install got it working.
Lots of work removing (like bizman said) things that windows10 should not do, like automatically have internet explorer started (might have changed with a later release), and shutting down and uninstalling SKYPE and other programs not needed for a game computer.
What worries me is that the updates are not very consistent for an OS, with bugs and one BSOD'ed.