For over a decade, the graphics industry relied on a single “master” architecture scaled from massive desktops down to thin laptops. In late 2024, AMD shattered this paradigm. Welcome to the era of bifurcation. Our 2025 audit dissects the critical divergence between the efficiency-focused RDNA 3.5 (found in Strix Point and handhelds) and the ray-tracing powerhouse RDNA 4 (powering the Radeon RX 9000 series). Whether you are eyeing a Ryzen Z2 handheld or building a custom PC, understanding this hardware split is essential for choosing the right silicon for your workflow.

Note: If you buy something from our links, we might earn a commission. See our disclosure statement.

RDNA 3.5 vs RDNA 4: The Complete Silicon Audit | Faceofit

Audit: Oct 2025

Architecture Audit

Radeon’s Great Divide: RDNA 3.5 vs RDNA 4

2025 Roadmap Shift: AMD has officially deprecated the “Unified Architecture” model. The company now utilizes two distinct silicon layouts: Mobile Efficiency (RDNA 3.5) and Desktop Fidelity (RDNA 4).

The industry standard for a decade involved designing one master graphics architecture for high-end desktops and shrinking it down for laptops. This method often resulted in inefficiency for mobile parts. AMD replaced this strategy with a bifurcated approach in late 2024.

Integrated & Mobile

RDNA 3.5

The Efficiency Mandate. Found strictly in Ryzen AI 300/395 processors and handhelds like the Ryzen Z2 Extreme.

Texture Subsystem: Double sampler rate allows higher texel fill-rate at lower clock speeds.
Voltage Curve: Optimized specifically for the 15W-50W window.
Memory: Reliant on LPDDR5X system memory (Unified).
Die Space: Removed legacy hardware scheduling to save silicon area.

Discrete & Desktop

RDNA 4

The Fidelity Mandate. Found strictly in Radeon RX 9000 series cards. Built to repair ray tracing deficits.

RT Engines: New “Double Intersect” engine handles 8 boxes per cycle.
AI Matrix Cores: Hardware support for FP8 and Sparsity (required for FSR 4).
Memory: Dedicated GDDR6 VRAM with Infinity Cache.
Scheduler: Reintroduced hardware scheduling for high-draw call scenarios.

Under the Hood: The Silicon Split

The divergence is not just about branding; it is about physical transistor layout. Below is the breakdown of the three critical subsystems where RDNA 3.5 and RDNA 4 differ most.

The Ray Tracing Engine

RDNA 3.5 uses a tweaked version of the RDNA 3 engine. It lacks the complex intersection logic to save power.

RDNA 4 implements a new Ray Box Sorter and Double Intersect Engine. It can process larger Bounding Volume Hierarchies (BVH) in hardware, reducing the load on the shaders. This targets parity with NVIDIA’s RT cores.

Memory Controller

RDNA 3.5 is bound by the 128-bit (or 256-bit on Halo) bus of the CPU. It relies on aggressive texture compression to minimize traffic to system RAM.

RDNA 4 utilizes a dedicated controller for GDDR6. It retains the Infinity Cache (Mall) to amplify effective bandwidth, a feature removed from most RDNA 3.5 dies to save space.

AI Acceleration

RDNA 3.5 offloads AI to the XDNA 2 NPU on the CPU die. The GPU itself minimizes matrix logic to stay cool.

RDNA 4 embeds Matrix Cores directly into the Compute Units (CU). This allows zero-latency access for FSR 4 upscaling without sending data to an NPU.

The Cache Divergence: Infinity Mall

One of the most drastic physical differences involves the “Infinity Cache” (MALL – Memory Access at Last Level). This large cache block was a hallmark of RDNA 2 and 3.

RDNA 3.5 Strategy

Removal. To fit more CPU cores and the NPU onto the die, AMD physically removed the MALL cache from standard Strix Point APUs. The GPU accesses system memory directly. This increases latency but significantly reduces silicon area and static power drain.

RDNA 4 Strategy

Retention. Because RDNA 4 cards (Navi 48) use a relatively narrow 256-bit memory bus compared to high-end rivals, the Infinity Cache is critical. It acts as a bandwidth amplifier, keeping frequently used assets on-die to avoid hitting the GDDR6 bottleneck.

The Display Engine Discrepancy

One distinct advantage RDNA 4 holds over RDNA 3.5 is the implementation of the “Radiance” display engine. While both support DisplayPort 2.1, the bandwidth varies.

RDNA 3.5 (Mobile): Typically limited to UHBR10 (40 Gbps). This is sufficient for 4K 120Hz displays found on laptops.
RDNA 4 (Desktop): Supports full UHBR13.5 (54 Gbps) in the mid-range. This allows for 8K 60Hz or dual 4K 240Hz monitors without heavy compression.

Architecture Efficiency vs Power Scale

Visualizing the “Crossover Point” where RDNA 4 takes over from RDNA 3.5.

RDNA 3.5 (Mobile Optimized)

RDNA 4 (Desktop Optimized)

Comparative Specifications

Specification	RDNA 3.5 (Integrated)	RDNA 4 (Discrete)
Codename	Strix Point / Strix Halo	Navi 48 / Navi 44
Process Node	TSMC 4nm (N4P)	TSMC 4nm (Optimized Libraries)
Ray Tracing Hardware	Gen 2.5 (Software Fallback often)	Gen 3 (Double Intersect Engine)
SIMD Structure	Dual Issue Wave32 (Legacy)	Single Issue Wave32 (Speculative)
Upscaling Tech	FSR 3.1 (Compute Shader)	FSR 4 (AI Matrix Hardware)
Display Engine	Radiance (DP 2.1 UHBR10)	Radiance (DP 2.1 UHBR13.5)

The RDNA 4 Silicon Matrix

Unlike previous generations that aimed for the flagship “900” class, RDNA 4 targets the high-volume mid-range.

Chip Codename	Market Segment	Target Resolution	Bus Width
Navi 48	Performance (RX 9800/9700)	1440p High Refresh / Entry 4K	256-bit GDDR6
Navi 44	Mainstream (RX 9600)	1080p High Refresh	128-bit GDDR6

Media Engine Capabilities (VCN 4.x)

Both architectures utilize the Video Core Next (VCN) engine, but configuration differs based on thermal headroom.

AV1 Encoding

Both platforms fully support AV1 hardware encoding. This is standard across the AMD stack for 2025.

Stream Count

RDNA 4 (Desktop) enables dual simultaneous encode streams for pro-streamers. RDNA 3.5 (Mobile) is typically locked to a single high-quality stream to prevent thermal throttling.

Performance Verdict by Category

Category	Winner	Reasoning
Battery Life (Wattage)	RDNA 3.5	Superior performance-per-watt below 30W due to removed legacy hardware.
Ray Tracing	RDNA 4	Double Intersect Engine creates a generational leap in lighting calculations.
AI Upscaling	RDNA 4	Only RDNA 4 has the Matrix Cores required for the AI-based FSR 4.
Cost Efficiency	RDNA 3.5	Integrated design removes the need for a separate GPU purchase and cooling solution.

The Road to UDNA (Reunification)

RDNA 4 is a transitional architecture. AMD has announced plans to merge the RDNA (Graphics) and CDNA (Datacenter) architectures back into a single platform named UDNA post-2026.

2023

RDNA 3 The last Unified Consumer Architecture. Used in both RX 7900 XTX and handhelds.

2024/25

The Split RDNA 3.5 (Mobile) and RDNA 4 (Desktop) launch separately to optimize for specific voltage curves.

2026+

UDNA AMD plans to reunify the stack, simplifying the developer ecosystem and driver stack similar to NVIDIA’s CUDA.

Technical Glossary

Intersect Engine Hardware unit that calculates where light rays hit 3D geometry. Doubled in RDNA 4 for better Ray Tracing.

FSR 4 FidelityFX Super Resolution 4. Uses AI to upscale images. Only RDNA 4 has the hardware to run it efficiently.

Unified Memory System RAM shared between CPU and GPU. Standard for RDNA 3.5, eliminating the VRAM bottleneck for AI models.

Strix Halo An enthusiast-class mobile APU that uses a massive RDNA 3.5 GPU to rival discrete laptop graphics.

Frequently Asked Questions

Does RDNA 4 support GDDR7?

Most initial RDNA 4 cards (Navi 48) utilize high-speed GDDR6 (up to 20Gbps) rather than GDDR7. This decision helps maintain cost effectiveness in the mid-range segment while still providing sufficient bandwidth.

Can I use FSR 4 on RDNA 3.5?

Likely not, or only via a slow software fallback. FSR 4 is designed for the specific AI Matrix Cores found in RDNA 4. RDNA 3.5 will continue to rely on FSR 3.1 which uses standard compute shaders.

Why did AMD skip “High-End” RDNA 4?

AMD cancelled the high-end “Navi 41” chip to focus on volume sales in the mid-range market ($400-$600). They are ceding the ultra-enthusiast segment to NVIDIA for this generation to rebuild market share.

Is the PS5 Pro RDNA 3.5 or RDNA 4?

It is a custom hybrid. It uses the rasterization engine of RDNA 3 but grafts on the Ray Tracing interconnect headers from RDNA 4. It does not fit cleanly into either category.

Affiliate Disclosure: Faceofit.com is a participant in the Amazon Services LLC Associates Program. As an Amazon Associate we earn from qualifying purchases.