You shouldn't install them to the default hard drive, you should create a steam library on the secondary drive. This is how you should be installing games; the SSD is for your Windows install, since it'll boot much faster, and any important programs (like Office, Chrome, general things).
Games, however, should be installed to the second drive as it will be much higher in capacity (usually), and the slower speed makes less difference for games since most don't generally take advantage of any faster speeds.
https://support.steampowered.com/kb_article.php?ref=7418-YUBN-8129 < Follow this to create a new Steam Library on your second hard drive, and make it your default so all games install there.