Internal hard drives not showing up on reinstallation of windows 10

Did i find a solution?
Yes and no.
I started unplugging all the drives and then plugging each one in in turn. Sometimes - not every time, but sometimes a neassage 'reboot and Select proper boot device or insert boot media and select bot device and press key' kept coming up.
I removed all the internal drives and (using a caddy) moved all the contents to external drives.
At one stage I seemed to be finding that BIOS was revealing 2 hard drives that were not installed - after the CMOS battery had been replaced. The Gigabyte MB boasts 'dual BIOS'. Could the secondary BIOS be retaining historic settings?
Anyway I reset all the sata cables on the MB, and shorted the BIOS for 30 seconds, reformatted all the drives and made sure they're all GPT, reinstalled windows again on the ssd using the MCT and, one by one connected up the drives.
I've managed to bring up drives D,E and F but the daisy chain power cable is limited to 4 Ok for C - F. G is not showing up in disk management or BIOS. I cannot alter the boot order - fortunately it's picked on the ssd as the first.
None of the spare power cables from the power supply, nor any replacemnet Sata cables have brought back G.
I may have to leave it there. Annoying - not because I desperately need G - I don't, but because for a couple of years it was up and running fine, well almost fine.
I am concious that this whole issue started when I could no longer select system restore and then found it impossible to connect external powered hard drives and get them to show up on ThisPC, as they had been doing (although memory sticks popped up fine on 'this PC').
I have the job now of sorting through which apps I can happily dump and auditing and editing 10 years of data of various types.
This was an interesting exercise to start with, but the frustration factor has buit up over the last few days. I'm sure using the garden blower didn't cause any of these problems - though I shan't do it inside the garage in future!!!
It's still niggling me that that wretched drive G isn't working.

I also have a Gigabyte MB.
More than once, my computer began to act strange and it did not recognize a drive.
I did a BIOS re flash ("update" BIOS with same version) and everything came back to normal.

I suggest you do a BIOS update (F18i), even if it's the one you have.