SUBJECT: ROG G751JT (and probably other similar models) after installing WIN 7 Pro on SSD 850, using orig 1TB for 2nd drive sata.

Hi all! I just wanted to drop a workaround or "fix" to an issue I just had after I dumped 8.1 and put Windows 7 Pro on it.
I worked on this problem, trying every single suggestion I could find on these forums as well as others. FINALLY I figured it out on my own and wish to shar eit here.
SOMEONE will have this exact issue as I and this will be where the fix will be found 🙂 The least I can do to pay you all back for my lurking.

Down to business...
Windows 7 is installed in place of 8.1 (clean) after wading through all of the "enable CSM", etc to brute it in.
Once done and the working drivers are loaded (I used the wireless driver for win 7 64bit for the wireless adapter after OS install, then
I used all of the regular 8.1 drivers for the JT for everything else- all good.

PROBLEM: If one of you has an issue where the old, say 1TB mechanical that originally came on it is being used for 2nd sata drive for
storage cannot be seen or detected by the BIOS NO MATTER WHAT YOU DO... do this-

>> I tried this after all else failed:
At the top of one of the BIOS (V.602, be sure to flash if you haven't already!) menu screens is a line that says "Easy Flash"
Yes... go there, we will "joggle" its memory lol. Once in easy flash, you will see info on asustek system
and notice the column on left showing filesystems found for the flash utility... FS0, FS1, FS2, and so forth.
Look at each one- they are like directory trees, they ARE dir's... the one I found that fixed my issue was FS4, when i selected it
then showed files in tree structure that I knew I had stored on this slave drive that used to be my main with 8.1.
After doing so, I rebooted and next time around it came up showing the drive just fine 🙂
Once into windows, the OS had no problem loading the drivers for it and off I went.

I hope this helps someone! Happy travels, -T