North Bridge Frequency in CPU-Z too high

[xStampede]

I just bought a new comp and the motherboard runs my 1866Mhz at 1333Mhz by default.

CPU: i7 4790
Motherboard: Asus H97M-E (http://www.asus.com/Motherboards/H97ME/)
RAM: Crucial BLT2CP4G3D1869DT1TX0CEU Tactical 8GB Kit (4GBx2) (http://www.amazon.co.uk/Crucial-BLT2CP4G3D1869DT1TX0CEU-Ballistix-DDR3-1866-PC3-14900/dp/B0069OG1RM/ref=cm_cr_pr_product_top)

CPU-Z validation(idle): http://valid.x86.fr/j74bms

Picture of CPU-Z SPD:

At default 1333Mhz Ram the north bridge frequency in CPU-Z is variable depending on load from 300Mhz up to 3700Mhz, after i turn XMP profile on the ram is set to 1600Mhz, CPU-Z shows NR frequency locked at 3991Mhz, why isn't it adjusting according to load like at default 1333Mhz?

I set the ram back to default cause im afraid to damage the motherboard if NR frequency is that high, i have no experience with north bridge so im might be panicking for no reason, can someone help me and point me into the right direction?

 

[sora]

I would personally set the RAM back to default just to be safe.