Samsung is the one to look to for breakthroughs in mobile chip manufacturing, as a rule of thumb in the industry. SK Hynix, a division of Hyundai, never seems to be far behind, of course. Samsung's latest silicon first is no exception. They just announced the first 8GB RAM chip for mobile devices a couple of months ago, and SK Hynix is already there with their own version. The way these things normally play out is that the companies begin their planning phase around the same time, and Samsung finishes manufacturing first due to their massive manpower, which makes for a more diverse product lineup between competitors; since the competition is trying their darndest to beat Samsung out the gate or at least not lose too much ground, they can't really wait to see what Samsung pushes out and then simply copy it.
The first 8GB mobile RAM chip, of Samsung pedigree, runs at 4.26 gigahertz and is manufactured on a 10 nanometer process. Hynix's version is a bit lower-spec, which means you will be likely to find it in cheaper devices like Chinese phones and quasi-flagships aimed at subverting the bigger players. Hynix's chip is made on a 21 nanometer process, which means it's a bit less power efficient and gives off more heat. It also runs at a lower clock speed, being about 3.73 gigahertz.
The chip is made up of four 2GB modules, with a respectable bandwidth of 29.8 gigabytes per second. While it's not the best RAM chip out there, make no mistake; the thing is blazing fast, and any device it's featured in will have to feature some pretty awesome components for the RAM to be the bottleneck. For budget manufacturers like Hynix, performance that gets out of a device's way and fails to bottleneck is a pretty respectable goal. Hynix's chip may play second banana to Samsung's, just as Hynix plays second banana to Samsung as a chipmaker, but it's a fairly close second banana in this case. The Hynix chip also has an ultra low voltage variant that's due to ship out in the first quarter of 2017, while manufacturers and hobbyists can get their paws on Hynix's standard 8GB RAM mobile chip right now.