Concur with proposed Setup:
128 Gig SSD as an OS + Boot drive
512 Gig M4 SSD as a drive for Games and all files you want to run at SSD speed.
3 TB drive, For storage / Back up
NOTE - Put your Image of 128 Gig SSD (From Windows Backup - Located in control panel, System & Security, Backbup) in the root directory of the HDD.
How I have my three systems that have daul SSDs and a HDD.
SSDs should BOTH be on Intel Sata III (6) port. (Red) - SATA6G_1 (128 Gig SSD) and _2 (For 512 Gig SSD)... Caution Do NOT stick them on the ASMedia® ASM1061 controller Ports!!!
The HDD can be placed on the ASMedia® ASM1061 controller Sata III ort OR on the Intel Sata II port. The HDD will NOT perform better on a SATA III Port. ONLY Burst speed is higher on the sata III port. Side Note, Since SSDs are better on the Intel Sata III port, the ASMedia® ASM1061 controller is OK for the HDD, But if you have no need for this port you could disable it and use the HDD on the Intel Sata II port - Your call on that. So either SAGA6G_E1 OR SATA3G_1