Wanting to know which would be the best setup for performance in Windows 10 for DP45SG board.
1. AHCI-legacy bios-MBR partitions
2. IDE-UEFI bios-GPT partitions.
Apparently Intel did not make drivers for AHCI-UEFI-GPT configuration.
Intel didn't make Windows 10 drivers for either of these configurations; you are going to be running with Microsoft's generic driver regardless. Any performance gain using AHCI over IDE (or vice versa) is likely to be negligible. GPT vs. MBR is a decision to be made based upon drive size, not performance.