RAM 5GB installed 712MB usable ?

[iH Xenon]

Hi Guys, I recently reset my pc with a fresh boot of windows 8.1. before this my ram was working fine I 3-4GB usable of my 5GB. but after the reset my pc is only allowing me to use 712MB of the 5GB in my system. anyone know of anyway to fix this or what is the problem ?

 

[Vic 40]

Maybe also do a clear cmos?

Also look in the msconfig and under the tab "starting computer" (?) look under the "advanced options" and see if "max. memory" is unchecked=[strike]V[/strike]