I went through the qualified vendor list for any DIMMS of 16GB. There were some GSKILL dimms listed under DDR4 3000.

If your goal is to have the maximum amount of RAM please don't expect to run them at high frequencies also. The more memory you install is harder on your CPU.
3000 mhz may be difficult with 64 GB of RAM installed, there may not have been 64 GB kits to test when this platform was released, what I mean is 64Gb kits for the Z170 platform not the X99 platform, If the kit is not qualified on the Z170 platform you may be setting yourself up for disappointment as the 2 platforms have differences

TheSarge wrote:
Hey, I just got me a new ASUS Maximus VIII Hero motherboard and I'm loving it. However, I do have a few questions.

First off, the manual says that:

but there's only 4 DIMM slots and 4x8 GB is only 32 GB, not the maximum of 64 GB that the board claims it supports. So, how can I get 64 GB of RAM on this thing? Is the manual wrong in that it actually supports 16 GB sticks, or is it wrong in that it only supports a maximum of 32 GB?

That's correct.

Give it some time and more kits with 16GB modules will be available.