http://forum.asrock.com/forum_posts.asp?TID=8008&title=vram-ab350m-pro4
Just for reference where to find it.. BUT I have the ASROCK mobo the AB350M and it allows you to set it up to 16GB of v ram if you really want... it doubles each time up to 16GB for my computer. I have mine set at 4GB being I only have 16GB of ram anyway.. IT goes from like 512MB to 1GB, 2GB, 4GB, 8GB, then 16GB (and a few smaller ones) AND it defently does it as well. but I didn't see much of a reason to go past 4GB or vram for the system I have.
I have had NO issues with the board other then it did not like the m.2 SSD I have in the top slot.. it works perfect in the bottom slot. They did launch an BIOS update after I got everything setup that is supposed to fix that though but I didn't see the need to move the Samsung 960 evo up to the first slot being alll works just fine and dandy with it in the bottom slot. ONLY real grip I could say about it is the ram I have SHOULD run at 3200MHz but the system was not stable at that speed (though I have not tried it since the bios update at that speed) it works just fine at 2933 or something MHZ. also thats with the Ryzen 3 2200g in it.
IF you have room in your case I would go for the
https://www.newegg.com/Product/Product.aspx?Item=N82E16813157761 as that one would also work with the larger VRAM. I have had very good luck with ASRock boards.. I have 3 different systems I have built with their boards in the last 12 months and all are great. that one with the 2200G, one with the Ryzen 7 1800X (X370 chipset) and an threadripper 1950X (X399 chipset) from ASROCK and all are rock stable.
IF you can get a larger board I would really go with the larger motherboard with the X370 chipset being its better but I went with the cut down version in one computer being it was a small case.
https://www.newegg.com/Product/Product.aspx?Item=N82E16813157800 but that one IF you can put a larger motherboard in it.
The ASRock AB350M Pro4 has a lot of mixed review but for me its been great so far..
Just make sure you Update the bios if you get it then you can get the full VRAM choices like I found out. the one I had I think the max 1 or 2GB of vram for it with the original bios it had. but the recent one has up to 16GB.. Its also on sale on newegg for the next 7 days.