Motherboard: Notebook W65_67SJ I know it can support up to 16 GB, however I know not all systems will support an 8 and a 4GB stick. I couldn't find anywhere online that would specify. I would try it myself, but I'm worried it could potentially cause damage if it is not compatible.
If it can support 16 GB (8+8GB), then 8+4GB sticks should work. Probably just refuses to work without doing damage if that 12GB is not supported.
I think you should be ok, worse case scenario it won't work but i don't think it will damage anything. I'm running 32GB on an asus maximum VII motherboard with no issues