Yeah, you're losing some RAM to the onboard video. That's why you've got less than 2GB usable.
FWIW I don't recall seeing any MSI desktop motherboard in the past 6+ years that could actually make use of the error correction capabilities of ECC RAM; you're probably wasting your money. If you want ECC capability in a desktop board, you've pretty much gotta buy an Asus AM3/3+ mobo these days...
The years just pass like trains. I wave, but they don't slow down.
-- Steven Wilson