BIOS/RAM Question - Dell Optiplex

[MaxRebo]

I have a Dell Optiplex 780 on Win10 with the 03NVJ6 motherboard. I've found conflicting info about this motherboard in terms of RAM capacity. It's either max 8GB or 16GB, according to various sources. Note: I didn't do enough research before I bought new RAM. Didn't see the 8 figure until after I was having problems with the new ones. The new RAM is listed as AMD, even though I have an Intel CPU. My understanding is that it should still work, just maybe not at its full potential.

Currently I have a couple of 2GB sticks [old] in it. I bought 4-4GB sticks [new], making sure to match the current speed (1333MHz PC3-10600). The machine does not POST at all if I only put the new RAM in it (all or some; I've tried multiple ones in all the different slots), so I can't get to BIOS or anything. If I put in one old stick along with the new ones, it will boot to Windows, but will only recognize the old RAM. The BIOS (which is up to date) also only sees the old RAM. If I run Speccy, it sees all the RAM installed; same if I run Memtest 86. For instance, I'll put in one old stick and two new ones. BIOS and Windows will show 2GB. I run Speccy and it shows 10GB.

I guess my question then is two-fold. 

1) Does this mobo support more than 8GB? I would think that if the 4GB sticks weren't supported, Speccy and Memtest would just see the slots as empty. 

2) If it does support up to 16GB, is it possible to tweak the BIOS or install an alternate BIOS to get it to recognize the new RAM?