AMD supplies Vega chips of varying height and finish quality to partners

AMD’s Vega video cards can be supplied with two different chips, each with small differences in height. This may cause problems for coolers and could lead to damage to the dies.

The differences came to light because AMD had included a separate Vega chip, complete with hbm2 memory on interposer, in the packaging of the review samples that it supplied to tech media. The Vega chips are not simply stuck on a substrate, but are mounted on an interposer that enables a fast connection to the hbm2 memory on the same interposer. The interposer then sits on a substrate that is soldered to the PCB of the video card. We photographed that chip package together with the video card for the review. Colleague Hardware.info, which has shared our premises since the takeover by De Persgroep, also received such a package, but with a different separate chip as a surprise.

The different packages, with the molded version on the left and the unmolded version on the right

We have now placed both chips next to each other and noticed that they are not identical. One chip has a black border around the loose dies of Vega-asic and hbm2 stacks and the other does not have that border. Inquiries with a source in the hardware industry revealed that these are actually two different chips, one of the chips being a so-called molded version and the other an unmolded chip. This source confirms that not only are the chips sent to reviewers different, but manufacturers also receive different types of chips from AMD.

AMD would have engaged two companies to further process the chips on the interposer. One polishes the dies so that they are the same height and applies a glue border around and between the chips, the other does not. That edge around the dies can protect the individual chips from crumbling when a cooler is placed on top.

However, if we look very closely at the two chips, you can see and feel that there is a small difference in height between the two. The molded version is completely smooth and in total slightly lower than the unmolded version. There the memory chips are slightly lower than the Vega chip and the whole is slightly higher. Video card manufacturers should take this into account when designing their coolers to effectively cool both variants. In addition, it is suspected that card owners who want to install a water block would be better off with the molded variant, since it is completely smooth and less easily damaged. The part numbers would not show which GPU is used in video cards.