This is probably a horrifically badly phrased question, apologies if it is.

Got an HP Envy DV7 laptop here, as-bought it came with Windows8 then got the 8.1 update a bit later. Decided that it should get the Windows 10 upgrade, but as a fresh install on a new Samsung SSD, (used Belarc to get the Windows 8 key), mainly to get rid of the HP-supplied cruft.

Installed SSD and used a Windows Media Creator built USB key to to the install, which went fine. But when the first post-install reboot came around, it failed, giving an error that "no bootable OS was found". Suspected naff SSD, so I tried a better laptop drive, (the DV7 came with a 5400rpm drive - what the heck?!), and a Media Creator created DVD - same result - install apparently went well, but gave me a non-bootable OS. Then tried a known good Ubuntu 15.10 DVD, and same result, it installed but wasn't bootable. Google for "hp laptop 3f0 error" and you'll see that I'm not alone in having problems.

Before anyone shakes their heads in disgust, yes, I remembered to turn off Secure Boot, and even tried switching on the "Legacy Boot" option at one point. Nothing worked, but popping up a command line in the install setup (Shift-F10) did show that the previous install attempts HAD written what looked like an OS image to the disk, (i.e. I could see a C:\Windows directory containing files etc)

This morning, I swapped back in the original laptop drive and used Samsung's cloning tool to duplicate it to the SSD. Then swapped laptop drive and SSD and tried a boot. It worked! So then I did the Windows 10 upgrade that went fine. Well, other than Samsung's support tool deciding that my IRST-equipped laptop was not running it's SSD in AHCI mode, but IRST reckons that the drive was running at the full 6Gb/s.

What's bothering me is that my main-Windows/gaming PC is due for it's half-decade total strip and rebuild. So am I utterly wasting my time trying to do a fresh install on my new hardware? Because the OS image wasn't bootable I never got asked for any key - so I'm reasonably sure that this isn't it. The only thing that occurs to me is that the DV7 was presumably an OEM Windows8 install, whereas my gaming PC is Windows7 from a proper boxed set.

Anyone got any light they can shed on this? I've Googled TenForums, Tom's Hardware, etc until I'm puce in the face.