- You should tell more precisely what you observe
- First, what does the Bios tell?
- Check the cabling, master-slave jumpers, Bios settings...
- Download the disk test programme from the manufacturer's site, let test.
One of the many many possible reasons: a few Bios from that epoch had a bug at 32GB, especially the infamous Award 4.51pg - but it used to see the disk, just limiting its capacity to 32GB.