Well I started to have some strange crashes from some programs and this morning my PC just turned itself off.
I really expected it to be a memory problem so I needed to enable memtest86+ on my new fedora installation.
I quickly found http://fooninja.net/2011/05/05/loading-memtest-from-grub-fedora/
This is still valid.
title Memtest86+ (4.10) root (hd0,4) kernel --type=netbsd /elf-memtest86+-4.10
to the end of the
/boot/grub/grub.conf and reboot