I had this problem for over two years I had no idea what was going on when the PC goes in standby mode. The HDD drives in my system would grind like crazy the led light for my case would be solid red and the 6TB drives I had were making so much noise I had to put my games back on my 3TB drives because I didn't know what was going on the grinding sound is really noticeable it's causes by this Windows 10 program running called Superfetch but Microsoft renamed recently to Sysmain. I never disabled it before but now if I let my PC run while downloads are happening nothing is grinding. Basically I think this program exists to get everyone to buy SSD drives and making them think their HDD drives are inferior. Here is a simple video on how to disable it and to think I almost pulled the plug on some 2TB Samsungs glad I didn't. I'll wait till 4TB SSDs are under 200.00.