Installation errors on new HDD

I have a PC - buit by myself into a Corsair case on an ASUS PX79PRO motherboard and until recently running two hard drives on Windows 10. The C drive was 120GB SSD with an 80 GB backup D drive and after numerous 'your disk space is running low' messages I decided to replace it with a new 1TB Seagate Barracuda SATA 111 device. I removed both other drives and performed a new install after formatting the new hard drive.
Firstly I lost my Windows 10 and had to reinstall Windows 7 from a factory CD, so am loading Home Premium 64 bit. I loaded the CD, then the motherboard drivers, then the LAN interface, then ran Windows update and updated around 120 updates. All was working well.
I then downloaded Origin in order to play games on-line, but this directed me to the wrong folder and wouldn't let me play a particular CD, but only the library version which to cut a long story short was the wrong version. I couldn't work around it and after two days decided the only thing to do was to reload Windows 7 from scratch and this time leave Origin out of it.
I inserted the installation CD and removed all partitions, then reformatted so I ended up with three partitions - 100mb, 450 mb and 931 GB. This was done by the machine, not my choice.
I loaded all as before, but on the final restart after all the downloads were complete and installed, I got the "Reboot and select boot device" message. I couldn't bypass this at all. BIOS was showing two hard drives, one marked UEFI, and one CD drive.
I reinstalled all from scratch again, this time reformatting the drive yet again with new partitions. Same as before - works well until the final few installs, whereupon it gives me the reboot message again. again BIOS showed two hard drive icons, one with a UEFI message but neither works for the restart no matter how many variations I select.
I've also replaced the motherboard battery just in case, but its made no difference.
I don't know what I've done to the drive but need to get it back to the way it was first time, when all worked well and I messed things up on the reinstallation.
I must have read over a dozen 'how to' guides on the Net since yesterday but they all end up trying to sell me some wonder product to cure my woes.
Any help or pointers from the gurus here? All very welcome!

You are installing a 64bit windows as x86 doesnt support uefii are you booting uefi or legacy? I think your problem is leaving paritions on the drive wipe it so there are no partitions then let windows create them some details Installing Windows 7 on UEFI based computer | Ask the Core Team

Don't understand why you're changing a SSD by a HDD. As you have a desktop, you can have the SSD only for windows and programs and the HDD for data.
During installation you can move C:\users to D:\Users using Kari tutorial. All you need is on the zip file.
https://www.sevenforums.com/attachme...d-relocate.zip

Anyway, on BIOS, you must set Secure Boot and fast boot to disabled. In some MB, Secure Boot = other OS or CSM=enabled.

To install as UEFI - GPT (recomended), insert the Win7 64 bits installation DVD, and when POST, launch the Boot menu (F8?). It will give you two options to boot: Legacy and UEFI. Choose UEFI, go to install - advanced - Delete ALL partitions, make new partition. Win 7 will make 3 partitions.
- 100M - Fat32 UEFI partition
- 120M - RAW M$ reserved partition
- A large NTFS partition.
Install on the large NTFS partition.