Z77 Extreme4-M Shutdown Issue

[SilencerPG]

Hi, I have had an annoying issue since building my PC back in January. The PC simply will not fully shutdown from Windows 7, all of the peripherals (ie mouse, keyboard, monitor) are powered off but the box keeps running. I am leaning towards this being a motherboard issue but would like to rule it out either way.

I have an Asrock Z77 Extreme4-M (BIOS ver 1.80 (latest)) running Windows 7 64-bit Home Premium.

Other hardware in the system is an Intel i5-3570K CPU, 8GB Corsair memory, Sapphire R9 200 GPU.

Appreciate any guidance.