System restart after writing to IBM

My PC keeps rebooting itself whenever I try to write any significant amount of data to my IBM drive. I’ve got a dual-drive setup here—an 80 GB drive running Windows XP and a 200 GB one just for storage. I even tried pulling the larger drive out entirely to see if it was causing a conflict, but the system still kicks itself into a restart during heavy write operations on the smaller OS drive. It isn't some dramatic Blue Screen of Death or anything; the machine just straight up restarts like nothing happened. I've already done the whole deep clean, blowing out all the dust, so that shouldn't be the culprit. Ran HD Tune and it didn't flag any errors, and according to FanInfo, my temps are sitting pretty between 35-38°C (though HD Tune showed it hitting 41°C once). I also ran Memtest86 via the Hiring boot tool and everything came back clean. For the most part, the computer behaves totally fine; small file transfers go through without a hitch, but as soon as I push it with a larger write task, it's game over.

Maybe you should just do a fresh OS installation on that larger, newer drive and simply pull the small one out of the equation entirely.

Maybe they're just messing around with the cables too...

The IBM drives are basically the same age, and I did a totally fresh install after a full format. I actually tried putting Windows 7 on there first, but ended up rolling back to Windows XP since the hardware is pretty old school. It’s kind of wild because neither the OS setup nor any of the software installs gave me any trouble during either attempt. One little detail though—the smaller drive is running on SATA, while the bigger one is still stuck on PATA.