Dh55pj Problem

I have:

• Intel DH55PJ motherboard (socket 1156)
• CPU: i3-540 3.07Ghz x64
• RAM: Kingston 8Gb 1333Mhz (in each slot) DDR3 9-9-9-24 1.5v
• OS: I'm using Windows 8.1 with no problems but:

1. Windows shows that I only have 3.19Gb RAM available. I tried changing msconfig, "boot", "advanced settings", but it doesn't help me.

2. It's not possible to install or upgrade win 8.1 32bit version to win 10 32bit or win 64bit
I tried to install both Win 10 x32bit and win10 64bit from USB, from an external CD-ROM, and install Windows itself on another hard drive, and install on another computer then connecting the hard drive to the computer, NOTHING helps. When trying to install from USB or external CD-ROM, the computer restarts after a while. When trying to install Windows itself on another hard drive, the installation doesn't continue after restarting.

I also tried with 4gb RAM to each slot, but it doesn't changes anything.

Please help me someone...