PC turns on, but Windows won't boot

Hello.
Does anyone have any ideas on how to fix this...
I've been dealing with this PC issue for a while now; it’s hit or miss. A few different people have looked at it, but nobody can pinpoint the exact cause. We've swapped out almost everything—used parts for the motherboard, power supply, graphics card, even a fresh install of Windows—but nothing sticks. The only thing left is the hard drive. I suspect the drive might be the culprit, though I'm not entirely sure how a failing drive manifests or if a computer can even function with one that's damaged.

Sometimes it's painfully slow while I'm working, or data transfers crawl, or the whole system just freezes up. A quick reboot usually clears it, for a moment.

The breaking point was the other day. Everything seemed fine, then I clicked a link and the machine just died. Since then, it won't get past the initial startup screen.
Any thoughts on what the issue could be?

Windows 7, using a single hard drive with multiple partitions.

If the drive itself is physically trashed, you'll probably see it right at startup—it just won't boot. In those cases, I think the system ends up kicking you straight into the BIOS settings... though in my setup, it forces me into the UEFI menu since that’s the newer tech 😉

Anyway, you should run some kind of diagnostic tool—maybe HDD Tune or CrystalDiskInfo—just to see what kind of error it's throwing and how many bad sectors we're actually dealing with.
But honestly? It might not even be a hardware issue.

Sent from my Samsung Galaxy S series via Reddit

It’s exactly what Andrew Peterson2 was saying.

Hard drives don't last forever; they just eventually give up the ghost. And honestly? Those symptoms you're seeing are textbook signs of a dying drive.
Your best bet is to either burn a bootable disc with some diagnostic software to confirm your suspicions, or just pull the drive out entirely and test it on a different machine.

If that drive is actually hitting an error, you aren't going to be able to fix it. You'll just have to grab whatever data you can still salvage before it's gone for good, and then go buy a new one.

Thanks a lot for the input. I'll give it a shot. 🙂