I have been using my Intel 750 as my main drive for over a year now, it's brilliant.
I was able to install Windows 10 on it and lived happily.
The Intel 750 is a PCIe NVMe SSD that resembles this specific card.
A few days ago I decided I wanted to install Window 7 os on a new raid 0 drive I have installed in my computer. I wanted to use it for Duel Booting.
After changing some of the bios CSM boot options and disabling Secure Boot I managed to boot a Windows 7 install usb and installed on this new drive.
To disable Secure Boot I had to delete the PK Keys in the bios. More on that here http://www.tomshardware.co.uk/answers/id-2225322/asus-uefi-boot-utility-secure-boot.html
Ever since that, I can't find out how to boot back onto my 750. When installing the Intel NVMe drivers on the Windows 7 drive I can see all the files and use the 750 (E:).
All the files appear to be there untouched.
But even after messing around with lots of settings, I am unable to figure out how to boot back into it.
I did check the drive's health, but considering it has been running properly for quite some time I am certain that this isn't a "check compatibility", "check the connections" and "swap PCIe slots" problem. -It's in the recommended slot anyway.
Using EasyBCD to create a start up boot option for E: didn't work. It tells me that something has happened to \Windows\system32\winload.exe.
The Intel 750 does not show up in the bios' boot options.
It does however show up as a PCIe device.
I have followed Intel's Nvme_boot_guide pdf and copied their CSM settings since their bios picture matched mine.
I also tried following this forum post **FIX** Winload.exe Is Missing Or Corrupt (No Its Not)
But it doesn't seem to have helped from the Windows 10 install USB's cmd (X:\) or the Windows 7 hard drive's cmd (C:\).
Perhaps it is undiscoverable from the Window 10 USB because it doesn't have the NVMe drivers?
I have also created a Windows 10 boot usb and messed around with some of the options there. Not entirely sure what I was looking for, I messed around with a few options there but no miracles.
I have run out of ideas short of reinstalling Windows on the Intel 750 and praying that I will be able to boot off of it after that.
Thank you all for listening and helping me.