Internet speed going up and down.?

[tinymap376]

Hello,

Since today I've had some problems with my internet connection.
It's fluctuating between max 12Mbp/s and then like a couple of seconds later it's back to 63kBp/s
I tried resetting the router and going to my routers site and look through the settings but it all seems normal to me.

Any help would be great.

Pardon me for my English.
Did a full scan on my Pc no virus has been found. No background process is running, I am the only one using this connection.
I'm using a Wireless connection at the moment. (I also tried wired but had the same problem)

Specs of my pc:

Windows 8.1 64bits (6.3, build 6900)
Intel core i5-4670k @3.40GHz (4CPUs)
16384MB RAM
NVIDIA GeForce GTX770 TwinFrozr Edition
Changed Frequency of the router, Immediatly went back up to 16Mbp/s.