Dell Optiplex 755 Stop Integrated graphics from reserving RAM even with dedicated GPU

[wildblade360]

I have a dedicated gpu and 8gb of ram but I am limited to 7.9gb. the bios shares ram with the integrated gpu even with a dedicated gpu installed. I have the option enabled to disable the integrated when I have a add in graphic card installed but the on board video still reserves ram.

BIOS:
http://www.dell.com/support/home/us/en/04/Drivers/DriversDetails?driverId=2DWTY&fileId=3104076313&osCode=WW1&productCode=optiplex-755&languageCode=en&categoryId=BI