AMD's Ryzen Mobile APUs are some of the most exciting products to launch in the PC space this year, and as enthusiasts, we wanted to channel that excitement by getting a review of one of those systems for our readers as quickly as possible. Our initial results showed promising performance for the chip, but some potentially less-promising numbers for battery life.

We've been trying to get to the bottom of those figures as we spend more time with the system, and in the course of that work, we have learned that one fundamental premise of our initial review was incorrect. AMD got in touch this morning regarding our results and officially confirmed that the Ryzen 5 2500U inside the Envy x360 we tested uses Mobile XFR, which is to say that it has a 25W TDP instead of the 15W envelope that was widely reported ahead of the system's arrival on the market. Here's the official line from the reviewer's guide:

Not all notebooks with the AMD Ryzen™ mobile APU will offer the necessary thermal solution to enable the performance upside of mXFR, but the HP ENVY x360 featuring the AMD Ryzen™ Processor with Radeon™ Vega Graphics is the first solution to do so. Users will look for “amplified mXFR performance” in the marketplace should they desire a laptop that offers this capability.

That new information significantly affects our analysis of the performance and performance-per-watt characteristics of the Envy x360 versus the 15W implementations of the Core i5-8250U that we tested it against, and I'll be incorporating this information into some updates throughout my original article as quickly as I'm able.

From AMD's reviewer's guide and in conversations with David Kanter for an upcoming podcast, though, we know that Mobile XFR primarily affects sustained workloads, and it probably means that the Ryzen 5 2500U may only achieve performance parity or fall somewhat behind the i5-8250U in multithreaded workloads in a 15W implementation. We really won't know until systems configured to use 15W versions of this APU show up for us to test. For now, buyers will want to take this new information into account as they weigh the Ryzen-powered version of the Envy x360 against the competition.