I first noticed this when I only had 8 GB of RAM and have sense then added 8 more.
With 8 GB of RAM the game would handle 1v1 games against the AI on normal difficulty and 4 player FFA for limited time.
The game would crash about 30 minutes into a 4 player FFA and go right to the desktop. After this happened a couple times I started checking the windows system monitor and noticed that after the game crashed there was a large amount of memory usage in standby and according to MSI Afterburner the memory usage during game play was close to the 8 GB I had available.
I added 8 more GB of RAM and now I can make it through 4 player FFA matches, but 5 player FFA matches on normal crash about 2 hours in, just about the time the army sizes are starting to get pretty large. It has similarities to the crashes I experienced with 8 GB of RAM. Large amounts of RAM usage in Standby and crashing straight to the desktop.
I have also began checking the system RAM usage after completing a game and exiting Ashes and there is still a large amount of RAM usage in standby (~6 GB). And it does not appear to matter whether I'm playing under DX11 or DX12. Not sure if this has already been brought up before, but I thought this would be worth noting.
My current system specs are Gigabyte Gaming 7 Mobo, i7-6700k, 16GB Adata DDR4 3300 MHz, AMD 290X, 1TB Samsung SSD Main Drive, and Creative SoundBlaster X7 External Sound Card