It might be trying to use one of your devices that you have hooked up through USB. Disconnect everything from your USB ports and try that.

You won't be using that unless you have a motherboard,case,and powersupply that will support it.

Should post the specs of the machine, then you can get accurate recommendations.

If you're going to just buy that as it is, you're getting nothing really.

Update the graphics card, the ram, and the powersupply. If you're gonna have a ton of games get secondary hard drive. Also ...

Looks like some glue, or heat-compound that got misplaced.

I see that all the time on electronics, it could also be there intentionally to minimize ESD.

It's not your hard drive failing...

If it was, you'd be hearing a clicking noise, or it wouldn't boot at all.

It's most likely something is corrupt with the operating system, or you have issues ...