What is the best free software...
 

I can use to check out the old hard drives I pulled out of our old set top boxes?

Is check disk still the one to use or is there something else out now?

This will be done using a Sabrent stand alone hard drive box via USB cable.

Thanks for any advice.

The drives are SeaGate 500GB SATA drives.

BIOS should catch any SMART errors

Otherwise a Linux Mint Live disk - boot the OS from it and gparted will be there (create/deal with partitions and filesystems) and hdparm (command line) can test read/write speeds and disk i/o

Western Digital offers a free download of theirs, I've used various versions for years.

I went ahead and formatted the drives via USB port. First drive took quite a while since I used a USB 2.0 port to connect. I used a USB 3.0 port for the second drive and it went a lot faster.
I would think if there were problems with the drives they would have shown up with a full formatting.
I did try down loading the Seagate software but couldn't figure out how to get it to see the drive via the USB port so went with a full format instead.
Thanks for the help.