Basically, there are molded and unmolded versions of the Vega GPU. The molded version not only has a black epoxy protection layer but this manufacturing partner also polishes the dies to ensure everything is the same height.
On the unmolded versions of the Vega, the Vega GPU is slightly higher than the HBM2 memory stacks. This means more thermal interface material (TIM) needs to be applied to the memory to ensure proper contact
AMD claims both versions of Vega are functionally identical but a look at photos posted by Tweakers.net reveal there's indeed a slight height difference.
![AMD Vega unmolded](https://www.dvhardware.net/news/2017/amd_vega_molded_vs_unmolded_1.jpg)
![AMD Vega molded](https://www.dvhardware.net/news/2017/amd_vega_molded_vs_unmolded_2.jpg)
As a consumer, it's not possible to know if you're buying a molded or unmolded version. There's no way to identify these cards. At the moment, we're not sure if there's a statistically significant thermal (or overclocking) difference between the two versions.
The only thing we know for sure is that it complicates things for AMD's add-in board partners and for consumers who want to install an aftermarket cooler. Unmolded versions of Vega are a bit more fragile and will need more attention when applying thermal paste.