Disk Management is a default Utilities to check your computer internal and external storage. You can also use it to format, create, delete partition and resize your partition. If your computer does not recognize a new hard disk - external or internal hard disk, you just need to open disk management and assign the volume letter for it. However if your hard disk not showing up in disk management you need to re-format the Hard Disk.
The problem is how to format it if it does not shows up in disk management?
1. Before we start make sure your Hard Disk cable (Sata/IDE) it is tight and connected properly.
2. Make sure the Hard Disk detected in BIOS.
3. There are 2 ways to format it, first by installing Ubuntu (or other linux distribution).
-Boot to linux/ubuntu and reformat your HDD
4. Get an External Hard Disk Casing (It is cheap, around USD10).
5. Make your Hard Disk as external and reformat it.
There are another way to fix this however it is depend on your situation. If you have a secondary desktop, try the HDD on the other desktop. If it is detected try to reformat it again. If your BIOS does not show your HDD it means either you have a loose cable or faulty HDD. Faulty motherboard could be the issue but it is a very rare case. Lastly RAM will not cause this, if you have faulty RAM it will only interrupt Windows Installation or cause BSOD.