I haven't been installing new hard drives in 4 years, or so, and I'm feeling very rusty.

The hard drives show up in the BIOS, I could have (I think) installed the OS onto them, but once in windows, they don't show up.

Any suggestions?

Try this if on Windows 7.

Start > right click computer > click manage > go to storage > disk management.

Look for them in that menu.  It is possible you need to format them there.  Also from within the same area you can go to Device Manager and then right click your computer name and Scan for Hardware Changes.

are these in a RAID array? do you have a working copy of windows or are you trying to do a reformat?  need a bit more information before we can give good advice...

if you are reformatting completely, you may need to insert the disk that came with the motherboard, and install any necessary drivers, such as RAID controllers, etc.

if you are operating from a second drive with a copy of windows, use Tet's suggestion. the drives should show up there, and you can format them or otherwise get them operational.

SFC.Braxis*BK*

Tet is 100% correct.  If you are added drive to a system that has already been imaged, then you need to format and assign the drivers to the system OS.  The instructions he gave you are correct.  Once you see the drives in the disk management, but right click and use the menu items, once of them should be something along the lines of add to OS or something like that.

Or it could be that the system did not give them a default drive letter and you need to assign them one. This can also be done in disk management. That has been the problem I have had with the system I am on now.

First advice got them rocking.

How do you guys do it, when your C is an SSD with little or no space, and you put all the other stuff onto the spinners? Is the hassle of changing the drive number during all installations the price you pay for a faster boot-up, or is there a shortcut somewhere, so that by default all installations take place on F: drive instead of C

Most program's will give you a choice of where to place your program/data at first install. Some also let you move them later.
Unfortunately, most times it is a hassle so trial and error I'm afraid.

My Setup:

OS Drive: 300GB SSD -  This one I have the OS and my main programs but not much only 184GB used.
Storage drive: 1.5TB - This is mostly for my games and some small files, but they all route through the SSD to be used like a buffer so my saved data is quick and trickles to the storage drive.
Server: 7TB - I store all my main data here. pics, movies, music.  I only use this for storage, but its network(via wifi) through the house so I can access everything with my TV, iPads and laptops.

It is a small pain to know where you want to put everything and drive letters and all, but after you do it for alittle while you will get used to it.

Do you have Steam installed on your main drive?  There's a guide somewhere on the forums on how to move it all to another drive with minimal hassle.  I did this and have not had any issues.  I also use dedicated drives for backups for things like all my game folders, programs, music, and movies.

On a side note, if you plan to keep backups of certain things like World at War user profiles,  I use a program called Syncback to automatically backup my Steam, Origin, and WAW folders.  Makes reinstalls easy.

I just want to say that I think you lot rock with your advice sessions team! Good job all of ya!