Ryzen 1600 overclock

So I tried overclocking my R5 1600 to 4GHz, I enabled A-XMP, I set the voltage at 1.4V, CPU frequency at 4000 (I have an MSI motherboard) and nothing else. I boot into windows and my clock speed is stuck at 1.36GHz on the task manager and CPU-Z shows that my core speed is at 1549.63MHz. What...