Mic volume reducing as I am talking

what happnes is that I will start up a VOIP service like Skype, Steam Voice chat or mumble the start of my sentances (the first 2-5 words) can be heared fine by the others in the chat however anything I say after that has the audio volume redused to a point where it is practically inaudible. reinstaling audiodrivers has not aided in resolving this issue nor has changing the pickup of the microphone in the control pannel settings, this has only started happening a few days after building my new computer, it was working fine for the first few days and has only started doing this recently.

the motherboard is an Asus Maximus VII Gene and the headset is a Steel Series Siberia V2 (not the USB one)

For testing, try the Windows Recorder and see if the voice level drops with that.

Also, try the PINK mic jack on the rear of the PC to see if works OK.

Windows recorder is picking up nothing even when using the headphone jack on the back

Do you mean the Microphone jack, and not the headphone jack?

Do you have the "Stereo Mix" set as the default recording device? I used to have a Gigabyte Z77X UD5H motherboard which has RealTek on it. I didn't have any audio problems.

the headset is connected correctly to the back of the motherboard though I have been lead to belive that the new motherboard sound driver may need fully uninstaling and reinstaling as there is a chance that it may be conflicting with the old audio driver from my previous motherboard however in device manager I click uninstal and the driver does not uninstal

If you install a new RealTek driver, the first thing it will do is uninstall the old driver, have you reboot the PC and then install the new driver.

What do you have listed in the Device Manager? You should have RealTek and possibly an NVIDIA HD Audio driver for HDMI audio. You may also have an Intel HD Audio (for the CPU). Shouldn't be anything else.

Try installing the R2.75 High Definition Codec driver directly from RealTek. That is the one I used on my Gigabyte motherboard and what I now use on the motherboards I'm using
Realtek

Skype (and possibly others) has "Automatically adjust microphone settings", it may be overreacting and lowering volume, set it manually and see what happens.