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#31
What choices are available when you click on SATA configuration in the BIOS Advanced tab?
It's possible since you have matching HD's they are configured in a RAID which could be the problem. Check what the SATA setting is. You want AHCI with one HD to try install.
When you were using 32 bit did you have a second HD showing in Explorer or Disk mgmt?
Are your HD's easily accessible where you can pull out one's power cable to try install?
Those are thumbscrews. If you feel like it unscrew them, unplug PC, hold power button to drain power, open door, study cables to HD and unplug one's cable. What's important inside a case is to never touch electronics without first touching the case, avoid touching the mobo at all.
Otherwise look for the setting in BIOS setup to disable one HD if at all possible.
Set SATA controller to AHCI.
Wipe HD with Diskpart Clean Command: SSD - HDD Optimize for Windows Reinstallation
After Cleaning, close Command Box, select Install Now, Custom Install, use Drive Options to create New 100gb partition, format, click Next. Report back what happens including verbatim error message.
The first pic is a thumbscrew and can be unscrewed with hand pressure.
If you see a series of them, most likely they control access to the case---removing them would let you remove at least one of the case's side covers and expose the innards.