Xiaomi Matched Apple's Cores. The Cores Still Belong to ARM.

Daniel Lemire posted that Xiaomi’s new CPU roughly matches Apple cores on single-threaded work and pulls ahead on multi-thread. The tweet hit Hacker News and collected 917 points in a day. The top of the comment thread did not argue about the scoreboard. It asked a blunter question. Who actually designed those cores?

The slide deck numbers

Xiaomi unveiled the Xring O3 on August 24. It is built on TSMC’s 3nm N3P node, on a 133mm² die with 24 billion transistors, up from 19 billion on last year’s Xring O1. The CPU is ten cores. There are no efficiency cores. Two ARM C1-Ultra cores peak at 4.35GHz, four C1-Premium cores at 3.68GHz, and four C1-Pro cores at 3.15GHz.

Xiaomi’s own Geekbench 6.5 figures are 3945 single-core and 15221 multi-core, up 31% and 61% from the O1. AnTuTu V11 is listed at 5,228,014. On-chip cache adds up to 44MB (12MB L2, 16MB L3, 16MB SLC). Xiaomi also says this is the first mobile SoC to ship with LPDDR6, at 113.8GB/s.

On paper, that nicks the single-thread perch Apple’s M-series has held for years. Lemire read it that way too. He also noted Apple may announce its next chip soon, so any edge might not last.

The floorplan still says ARM

The highest-ranked HN comment was short. This is still an ARM C1-Ultra. The same core is in MediaTek’s Dimensity 9500, which cleared 4000 on a Geekbench 6 lab run and then landed closer to 3300 once it was in a phone, under phone cooling and a phone power budget.

Calling a chip “in-house” is not the same as drawing the CPU cores. What Xiaomi did is SoC work: how many cores to glue on, how much cache to park beside them, how to drop memory, NPU, and GPU onto one die. The C1 cores themselves are an ARM product, sold under license. That is a different craft from Apple drawing A-series and M-series cores from scratch.

Beebom’s write-up draws the same line. The Dimensity 9500 is an eight-core part with one C1-Ultra and three C1-Premiums. Xiaomi doubled the Ultras and went to four Premiums. That is plenty of reason for the multi-core number to jump. MediaTek’s top clock is 4.21GHz. Xiaomi’s is 4.35GHz. The all-big-core layout is Xiaomi’s call. The single-thread jump is ARM’s new fat core.

Those 917 points split two ways. One story is that Android silicon has closed on Apple’s single-thread score. The other is that it closed because ARM shipped a new C1 generation, not because Xiaomi out-drew Apple’s microarchitecture team.

4000 in the lab, 3300 in a pocket

Beebom was explicit: these scores came from Xiaomi’s own lab. A retail phone can print a different number. The Dimensity 9500 already showed that drop.

One comment recycled the oldest mobile-chip joke. The first 15 seconds look brilliant. Then heat eats the score. Fifteen seconds is enough to launch an app. It is not enough for a long game session or on-device inference. Ten big cores with no little cores help a multi-core bench. They leave an open question about sustained heat. Xiaomi claims power draw falls as much as 25% versus the O1 at low-to-medium load. Whether that curve holds inside a foldable is a September problem.

Volume is not flagship-line volume either. Reuters sources put the O3 shipment target at 200,000 to 300,000 units. That is not the run rate of the world’s third-largest phone maker. First devices are the Xiaomi 18 Fold and the Pad 9 Pro Max, both due in September. Lemire’s aside still applies. You may have trouble finding a phone that actually has the next CPU.

In-house logo, MediaTek modem, Taiwanese wafers

TSMC fabs the O3. It also fabs the Dimensity 9500 on N3P. A Chinese company can own the design and still send 3nm wafers through a Taiwanese line. The press line about cutting Qualcomm and MediaTek dependence sits in the same sentence as “TSMC still makes it.”

There is a smaller tell. Beebom’s spec sheet lists a MediaTek T900 5G modem. The SoC badge says Xiaomi. The radio block is a competitor’s part. That is the context for the HN line that this is bad news for MediaTek and Qualcomm. The number-three phone vendor is now assembling a MediaTek-class SoC itself. It has not cut the modem yet.

The roadmap next to the bench slides is the larger story. The Xring O100 is a 6nm NPU meant to run Xiaomi’s MiMo language model on-device. The Xring D100 is a 3nm chip for autonomous driving. Xiaomi says the O3 is already in mass production, with the O100 and D100 due next year. The O3’s own quad-core NPU is rated at 200 TOPS on A8W4, up from 44 TOPS on the O1. That is a bigger move than another Geekbench screenshot. It is a bet that phones, on-device AI, and cars can live under one chip umbrella.

The South China Morning Post asked why Xiaomi is still pouring money into in-house silicon during a profit slump. Two answers sit side by side: grabbing the supply chain, and poking Apple with a bench slide. HN reacted to the slide. The supply chain is the part worth tracking.

Apple’s single-thread lead is not a law of physics. The slide still will not tell you whether the signal came from the Xiaomi logo or from ARM’s C1-Ultra. When the foldable ships in September, check what 3945 becomes in a hand, not in a lab.