AMD Graphics card has vanished after HDD replacement

Hi all - first post!
I've been running the same home-built PC for a number of years and upgrading components as I go along. I was on Windows 10 with two drives, a Seagate 80GB as backup and a SSD 120GB as the main drive. Everything was great until the warning messages started to appear about my hard drive being full, and to free up space. As I couldn't free any space I opted for a bigger drive and bought a Seagate Barracuda 1TB drive. Sadly when fitted I realised I'd lost my Windows 10 upgrade so had to revert back to Windows 7.
The PC now starts and runs but the graphics is 'standard VGA graphics' rather than the Powercolor RX480 8GB d5 3dh/oc card I had installed previously. I've tried to reinstall the drivers but it tells me I have no AMD device installed; device manager doesn't see it, but yet the card fans run and the audio is apparrently running through an AMD device so it seems the audio recognises it but not the graphics.
I can't find any way to swap the graphics in the BIOS as some have suggested; there's no option appearing on the ASUS BIOS page or menu. I've been at this for three days, trying every idea, swapping the PCIE slot about (it's an ASUS PX79PRO board), checking power is getting through, but to no avail. The card is just completely invisible.
Any thoughts before it all goes out of the window? I had no trouble at all until I swapped the HDD and reverted back to Windows 7.

Hi TriumphDriver.

Swapping out HDD's DOES NOT remove/invalidate your W10 licence,
Its only a small part of the activation process, and MS expects people to swap them in and out, so its peramaters are quite loose in this regard.
(if you have an image you can just transfer it to the new ssd)

Have a look in your device manager -
Other
Problem devices

As its an Intel MB its possibly running dual grahics.
You have to follow a precise install order
INTEL first - then your Graphics card drivers (card unplugged)

Roy

Thanks Roy; firstly - when I redownload Windows 10 it asks me for a key, without which it won't proceed. The drive it was on, the SSD 120Gb, has already been reformatted so all the details have been lost. (Windows 7 is activated already online and is a CD version so has a genuine key)
Regarding the graphics card - I'm not 100% sure how to install Intel first as the AMD card is the only graphics card I have installed, so there's nowhere else to plug in a monitor - no connectors on the rear of the motherboard. This is further confusing me as the monitor runs through HDMI from the AMD card that isn't there... there's nothing in device manager, not under display, other or problems. It just doesn't exist!
However: the audio is running through it as an AMD audio device in device manager... so it's there.. but not there....

I may have solved this one myself.... instead of using the Powercolor driver package which came with the card, or their current drivers from the Powercolor website which repeatedly told me that no card or product was installed, I went directly to the AMD Radeon website and downloaded the latest drivers, which worked first time. I now have the card listed in device manager and all sorts of resolution and settings options that I didn't have before.
All I need to do now is sort out the loss of Windows 10....

It may still be possible for you to upgrade to Windows 10 for free:

https://www.howtogeek.com/272201/all...s-10-for-free/