FIRSTLY,
this is a rumor—one that comes with a set of decidedly official-looking AMD slides apparently snapped from a monitor, and from a reliable source. This isn’t gospel, but it shouldn’t be far from what’s coming either, and is good news. Zen 5 will be a complete architectural overhaul, although the chip structure remains the same. The branch prediction has been redesigned, and gets zero bubble conditional branches (a system that handles a branch without delaying subsequent instructions). There’s more L1 cache, 50 percent bigger at 48KB. The throughput has been worked over, as has the scheduler and prefetch. All this rejigging is said to result in an IPC improvement of 10 to 15 percent.
AMD has traditionally been conservative with its IPC predictions. Zen 4 was supposed to give a bump of about eight percent, but it managed about 14. Current estimates put the actual increase at between 15 and 26 percent. We also get more cores. It’s expected that there will be two CCX designs: a 4nm version with eight full Zen 5 cores, and a 3nm one with 16 Zen 5c efficiency cores. One of each would give us a 24-core range-topper. There’s no news of V-Cache versions, but AMD will no doubt keep that trick for when it needs it.