A while ago I built a computer and it installed Windows 7 64-bit fine on it. But due to my RAM not working with both modules, I had to replace the RAM. Today my RAM came and I put it in, but my computer wouldn't boot from the hard drive.
I thought my hard drive was broken but it was being recognised in the bios settings, and so was my DVD drive.
So I tried to boot it from the AHCI DVD drive and nothing happened either, just a black screen with blinking underscore at the top left corner of the screen.
Then there was another option of booting it from something called UEFI DVD drive and that worked, prompting me to press any key to boot from DVD drive. However, when I go to the installation screen and format the partition it says 'Failed to format the selected partition 0x8004242d'. So I think that this isn't working because I booted it from the UEFI thing which I don't really understand.
This all worked fine before, when I tried to install Windows before it booted from the DVD just fine, there was no error code when I was formatting the partition so I can't understand why it's not working now.