Alright, wanted to give my follow-up to let everyone know the results...
Quick recap:
- PC has a Pentium 4 (Prescott) 630 3 GHz.
- PC had 64-bit Windows 7. Windows 8 Upgrade media installed 64-bit Windows 8 (no choice in the matter, you can only upgrade "same for same"; if you previously had 32-bit, you get the 32-bit upgrade). Been using Windows 8 since it debuted.
- Went to the Windows Store to upgrade to Windows 8.1. CPU failed requirements check.
This is the new system requirement that is present in Windows 8.1 but not present for Windows 8:
"To install a 64-bit OS on a 64-bit PC, your processor needs to support CMPXCHG16b, PrefetchW, and LAHF/SAHF"
My CPU failed the last two requirements and thus would not allow installation of 64-bit Windows 8.1.
My solution:
- Formatted the HDD and installed 32-bit Windows 8 from my upgrade media (using the tutorial here at eightforums).
- Note that the tutorial said I needed to do some steps to activate a fresh install of Windows 8 using upgrade media.
THIS STEP WAS NOT NEEDED. When I went to System, it said my Windows was already activated.
- Then upgraded to Windows 8.1 via the Windows Store. I tried the 8.1 ISO method (mounting it and then running setup.exe but it failed to recognize my Windows 8 key and I didn't have a Windows 8.1 key).
Now the system works great with 8.1! My father is using it with a touchscreen monitor and the improvements to 8.1 really helped.
Want to give special thanks especially to
DavidY (thank goodness there's someone that reads system requirements in their entirety!) and
my2cents! You guys were awesome!
My father is still going to buy a new computer (prices are amazing nowadays!) but this should extend the life of this current one. In case anyone wanted to know, he's buying a new fully loaded desktop PC with Haswell Core i7 with 16 GB RAM, DVD burner, etc. for less than $700! It's a great time to get a PC.