Can I create a RAID mirror with 2 by 4Tb discs?

I have 3 RAID mirrors, 2 X 2Tb and 1 X 1.5Tb.

The small mirror (1 X 1.5Tb) degraded so rather than replace the dead 1.5Tb (after securing the data) I deleted the volume and bought 2 X 4TB drives.

Replaced the 1.5Tb discs with the 4Tb discs and double clicked on the Intel Rapid Storage Technology icon and loaded the program which saw the new discs as 3,815Gb drives

I then created a new RAID mirror, no problems. BUT, the display shows the 3,815Gb discs but the mirror size is only 1,718Gb.

Could someone, more conversant with the topic, please confirm that RAID mirrors are limited to 2Tb? As it appears that my new mirror has lost a factor of 2Tb.

I contacted Gigabyte (the manufacturers of my P55A-UD7 motherboard) and they suggested that I SHOULD be able to build 3Tb mirrors. It seemed strange to me that they couldn't say if the MB could or couldn't handle larger that 2Tb mirrors, after all they are the manufacturers

Maybe someone more aware of Intel limitations can answer my query?

My MB (and whole system) is a couple of years old and I am running Windows 7 64bit with 8Gb ram.

Thanks in anticipation

PS I got a message that the drivers for the 4Tb discs failed to load!?

Thanks for your response :)

I am aware of the rules with > 2Tb drives, I have 2 internal 3Tb, lots of 3Tb and a 4Tb external hard drives all setup and running happily as JBODs.

I am asking specifically about RAID mirrors which are a different kettle of fish