AMD Ryzen 9 5900X3D engineering sample surfaces with a single 3D V-Cache stack and 128MB of L3 cache

Q: What benchmark results have been reported for the 12-core Ryzen 9 5900X3D engineering sample?

No benchmark scores are reported for the 12-core Ryzen 9 5900X3D engineering sample. The reported figures are a CPU-Z clock reading of roughly 4.65GHz and some reports of a maximum as high as 4.85GHz, not performance test results.

Q: How does the Ryzen 9 5900X3D’s single-CCD cache layout affect gaming performance compared with the 192MB dual-stack prototype?

The Ryzen 9 5900X3D sample has 96MB of L3 cache on one CCD and 32MB on the other, while the dual-stack prototype had 192MB across both CCDs. The single-stack sample shows a higher clock speed, but no gaming benchmarks are reported, so the effect of that layout on gaming performance is unknown.

Q: What clock speeds does the Ryzen 9 5900X3D sample sustain under gaming and other real-world workloads?

The Ryzen 9 5900X3D sample reads roughly 4.65GHz in CPU-Z, and some reports put its maximum as high as 4.85GHz. Neither figure establishes what clock speed it sustains during gaming or other real-world workloads.

Q: How did AMD’s later Ryzen 9 X3D processors for AM5 use the single-CCD V-Cache layout?

AMD's later Ryzen 9 X3D processors for AM5 put the extra 3D V-Cache on one chiplet and left the other without a cache stack. The Ryzen 9 9950X3D2 Dual Edition was the later exception, with cache on both chiplets.

A 12-core Zen 3 X3D chip that AMD never sold has turned up in China, and, interestingly, it clocks higher than the prototype shown in 2023.

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Hassam Nasir

Senior Tech Reporter

Published Oct 2, 2026 1:45 PM CDT

1 minute & 15 seconds read time

TL;DR: An AMD Ryzen 9 5900X3D engineering sample has surfaced with 12 cores, 24 threads and 128MB of L3 cache, using a single 3D V-Cache stack. It reportedly boosts higher than AMD's earlier dual-stack prototype, but requires an older BIOS to run.

Voice: Hassam NasirSpeed

0:00 / 2:35

AMD first teased 3D V-Cache in 2021 on a 12-core Ryzen 9 5900X prototype, yet the only Zen 3 X3D chips it went on to sell topped out at eight cores. Now a Chiphell user has apparently got hold of one of the 12-core parts that never made it to shelves, and it isn't the version we already knew about.

The chip is an engineering sample of the Ryzen 9 5900X3D, marked with the code 100-000000652. Screenshots show 12 cores, 24 threads, a 105W TDP, and 128MB of L3 cache. That total comes from 96MB on one CCD and the stock 32MB on the other, so it looks like AMD stacked the extra 64MB of cache on just a single chiplet.

AMD Ryzen 9 5900X3D engineering sample surfaces with a single 3D V-Cache stack and 128MB of L3 cache 2

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The 5900X3D prototype that AMD showed Gamers Nexus back in 2023 had a stack on both CCDs, which added up to 192MB. The difference is notable, but the clock speeds are the more interesting part.

AMD Ryzen 9 5900X3D engineering sample surfaces with a single 3D V-Cache stack and 128MB of L3 cache 3

The dual-stack prototype was limited to a 4.4GHz boost, while this sample reads roughly 4.65GHz in CPU-Z, and some reports put its maximum as high as 4.85GHz. It seems like leaving one CCD bare gave AMD more room on frequency, though we don't know that for sure.

AMD Ryzen 9 5900X3D engineering sample surfaces with a single 3D V-Cache stack and 128MB of L3 cache 1

Running the sample wasn't easy, apparently. It reportedly won't boot on recent BIOS versions and needed an older one with SMU firmware 56.70.0. The owner has also reportedly asked ASRock to add support in a newer BIOS.

Story Q&A

From TweakTown's coverage of this story.

What benchmark results have been reported for the 12-core Ryzen 9 5900X3D engineering sample?

How does the Ryzen 9 5900X3D’s single-CCD cache layout affect gaming performance compared with the 192MB dual-stack prototype?

What clock speeds does the Ryzen 9 5900X3D sample sustain under gaming and other real-world workloads?

How did AMD’s later Ryzen 9 X3D processors for AM5 use the single-CCD V-Cache layout?

Want something else? Ask TweakBot.

AMD later used this same one-CCD layout for its Ryzen 9 X3D chips on AM5, and only this year did it unveil the Ryzen 9 9950X3D2 Dual Edition with cache on both chiplets. So the 128MB sample is probably closer to what AMD ended up shipping than the 192MB one was. AMD hasn't yet commented on the sample.

AMD Ryzen 9 5900X3D engineering sample surfaces with a single 3D V-Cache stack and 128MB of L3 cache

Story Q&A

What benchmark results have been reported for the 12-core Ryzen 9 5900X3D engineering sample?

How does the Ryzen 9 5900X3D’s single-CCD cache layout affect gaming performance compared with the 192MB dual-stack prototype?

What clock speeds does the Ryzen 9 5900X3D sample sustain under gaming and other real-world workloads?

How did AMD’s later Ryzen 9 X3D processors for AM5 use the single-CCD V-Cache layout?

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