Some motherboards such as ASUS P9X79 WS support something called “ASUS SSD caching”. You can connect 1 HDD and 1 SSD to 2 designated SATA ports, and IUUC, you can have a setup in which the motherboard will automatically cache (on the SSD) the most often used data stored on the HDD. It allows you to take advantage of the SSD speed and HDD capacity at the same time.
I saw a presentation on YouTube, in which they show how to set it up using a program running on Windows. I'm curious if this is really a hardware solution (can be used on Linux), or is it partially in software? If it were just hardware, you could install Windows, run the utility to set up SSD caching, and then install Ubuntu, benefiting from the caching setup? (Also, if it's a hardware solution, why not set it up in right in the BIOS?)