I posted elsewhere on this site regarding this topic, but because I used this thread to originally get myself educated, I wanted to provide some input and feedback. The answer provided is entirely correct: Using the ATA Password feature in the BIOS to use the hardware encryption feature of the Intel 520 SSD will be the fastest and most secure way to encrypt the disc.
Note: The Intel Toolbox software will NOT encrypt the disc for you. It will tell you if it's encrypted or not, but it does NOT provide the mechanism to create a password to lock the drive. To do that, you need a motherboard with a BIOS that supports ATA Passwords (which is separate and in addition to a BIOS password, BTW).
The problem is that Mobo makers don't advertise or mention whether they offer ATA Password encryption options. Anywhere. Mobo reviews don't mention it either. For a feature that would unlock the security potential of tens/hundreds of millions of Intel and Samsung SSDs, you'd think someone would mention it. Nope. Nada.
So here's all I can offer. I have the ASRock Extreme6. It had no such ATA Password option. I wrote to ASRock tech support in Taiwan. In a week, they gave me an updated BIOS!!! I suspect they had it all along but didn't want to release it in case noobs locked themselves out of their hard drives. Anyway, if you have an ASRock motherboard, you can get this option, just contact ARock tech support in Taiwan.