In Graphics, revenue decreased year-over-year driven largely by lower channel sales partially offset by a significant increase in data center GPU sales. Radeon Vega GPU shipments grew by a strong double-digit percentage both year-over-year and sequentially based on increased adoption across OEM, gaming and data center customers. Apple introduced two new iMac systems featuring upgraded Radeon Pro Vega GPUs that deliver up to 80% faster graphics performance than the previous generation.
We believe we made good progress improving channel inventory levels. Sell-through accelerated sequentially driven by sales of both our mainstream Radeon RX GPUs and new high-end Radeon VII gaming GPUs. We are well-positioned to grow GPU revenue in the second quarter and through the second half of the year, as we expect to introduce our first 7-nanometer Navi gaming GPUs in the third quarter.
...we are excited about Navi. Navi is a new architecture for us in gaming. It has a lot of new features, across the Navi architecture. Things are progressing well. We expect it to launch in the third quarter.
From a positioning standpoint, I probably won't go through it in great detail right now other than to say that it is 7-nanometer, Navi, but it will be positioned below where, for example, our Radeon VII's is position today from a price point standpoint.
And then, in terms of Ray tracing, again, we will talk more about our overall Navi roadmap as we get closer to the launch.