September 30, 2022


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Ryzen 9 6900HX: Currently the strongest iGPU but memory bandwidth is still the bottleneck

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Ryzen 9 6900HX: Currently the strongest iGPU but memory bandwidth is still the bottleneck

Ryzen 9 6900HX core display test: Currently the strongest iGPU but memory bandwidth is still the bottleneck. 

In fact, when AMD released the Radeon RX 6400 graphics card in April, the first thing I thought of when I saw the specifications of the graphics card was not the RX 6500 XT, which is the same source as it, but the Rembrandt architecture Ryzen 6000 series they released in January.

Mobile processor , look at the RDNA 2 architecture used by the RX 6400. The Radeon 680M of the Ryzen 6000 is also an RDNA 2 architecture.

The RX 6400 has 12 sets of CUs, and the 680M also has 12 sets of CUs. The RX 6400 uses TSMC’s 6nm process, and Rembrandt uses it.

It is also TSMC’s 6nm process. Although it is not exactly the same, the similarity is very high.

When the RX 6400 was first released, we didn’t have a notebook with a Ryzen 6000 series processor on hand, so unfortunately we didn’t do a comparison test between the Radeon RX 6400 and the Radeon 680M.

Recently, the ROG Ice Blade 6 dual-screen gaming notebook we tested uses the Ryzen 9 6900HX processor, which can be switched to the core display mode, and the power of the core display can run to more than 50W, which is just used for this comparison test.

Specification parameter comparison

modelRyzen 9 6900HX
Radeon 680M
Radeon RX 6400Ryzen 7 5700G
Radeon Graphics
ArchitectureRDNA 2RDNA 2Vega
computing unit12128
GPU frequency2400 MHz2039~2321 MHz2000 MHz
light accelerator1212N/A
texture unit484832
grating unit32328
stream processor768768512
Video memory/memory typeDDR5
Video memory interface128-bit64-bit128-bit
Effective memory speed(DDR5)4.8 Gbps
(LPDDR5)6.4 Gbps
16 Gbps3.2 Gbps
Maximum memory bandwidth(DDR5)76.8 GB/s
(LPDDR5)102.4 GB/s
128 GB / s51.2 GB / s
H264/AVC decodingYesYesYes
H264/AVC encodingYesnoYes
H265/HEVC decodingYesYesYes
H265/HEVC encodingYesnoYes
AV1 decodingYesnono

If you carefully compare the Radeon 680M core graphics and Radeon RX 6400 independent graphics specifications, you will find that the GPU frequency of the Radeon 680M is even higher, and can run to 2400MHz, while the maximum frequency of the RX 6400 is only 2321MHz.

Of course, the RX 6400 is an independent graphics card. It has its own video memory.

Although there is only 64bit/4GB GDDR6, the memory bandwidth is higher than that of the Radeon 680M as a nuclear display.

The memory bandwidth of the Ryzen 7 5700G in the above table is calculated according to the official DDR4-3200, but it is a retail desktop CPU.

The frequency of the memory is basically determined by the user. If you use 3600MHz memory, the memory bandwidth should be 57.6Gbps.

In terms of multimedia engines, the RX 6400 is really weaker than the Ryzen 7 5700G with Vega core display. It has no video encoding function at all, nor does it support AV1 video decoding.

Although Vega core display does not support AV1 format decoding, but It supports at least H.264 and H.265 encoding functions. As for the Radeon 680M core display, it basically completely inherits the VCN 3.0 video engine of the RX 6000 series, and the encoding and decoding functions are relatively complete.

Testbed and Instructions

HardwaresTesting Platform
CPURyzen 7 5700G
motherboardMSI MPG X570S CARBON MAX WIFI Motherboard
graphics cardRadeon RX 6400
MemoryXPG Longyao D50 DDR4-3600 memory 16GB*2
hard diskTeam Group Leader EXPERT PCIe 2TB SSD
heat sinkYajun G3 air cooling radiator
power supplyROG Thor Power Supply 1200W
Software configuration
operating systemMicrosoft Windows 11 64bit build 21H2

ROG Ice Blade 6 Dual Screen

CPUAMD Ryzen 9 6900HX
GPUIndependent graphics: NVIDIA GeForce RTX 3080 Ti Laptop GPU (7424 CUDA, up to 1445MHz boost frequency, 16GB 256-bit GDDR6 memory, up to 165W TGP) Integrated graphics
: AMD Radeon 680M
MemoryDDR5-4800MHz 32GB*2
displayMain screen: 16 inches, 2560*1600 resolution, 165Hz refresh rate,
secondary screen: 14.1 inches, 3840*1100 resolution, 60Hz
storage2TB+2TB M.2 NVMe SSD(PCI-E 4.0,RAID 0)
interfaceUSB 3.2 Gen 2 Type-A*2, USB 3.2 Gen 2 Type-C*2 (one of which supports power supply), HDMI 2.1*1, 3.5mm composite audio*1, microSD card reader*1 (UHS-II), RJ45 wired network port*1
connectWireless: Wi-Fi 6E (802.11ax), Bluetooth 5.2 (dual-band 2*2)
operating systemMicrosoft Windows 11 Home 64-Bit

This test used two sets of platforms, namely the ROG Ice Blade 6 dual-screen gaming notebook equipped with the Ryzen 9 6900HX processor, and our first test platform of the Radeon RX 6400 at that time.

The CPU used the Ryzen 7 5700G for comparison with the previous generation. The performance of the nuclear display, the memory is DDR4-3600 16GB*2.

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