AMD Radeon RX 7900 XTX Review - Disrupting the RTX 4080

Introduction

The AMD next-generation we’ve long been waiting for is finally here! The new Radeon RX 7900 XTX in this review, and the Radeon RX 7900 XT, which we’re also reviewing today, debut the company’s 3rd generation RDNA graphics architecture, or RDNA3. With it, the company is also introducing the world’s first chiplet-based GPU in an effort to maximize utilization of the TSMC 5 nm foundry node, without compromising on performance, or too much on power. The RDNA3 graphics architecture promises a similar 50% leap in performance/Watt over the previous-generation RDNA2, which helped AMD compete in the high-end segment after a long gap of 7-odd years. The new architecture improves in many areas, including compute power, memory sub-system, display engine with support for the latest DisplayPort 2.1 standard, multiple-stream acceleration for the latest video formats, and most importantly, AI acceleration, and a more advanced ray tracing hardware.

AMD’s decision to leverage chiplets to build the new “Navi 31” GPU powering the Radeon RX 7900 series, has to do with attempting to keep Moore’s Law alive in spirit. The idea is to achieve high-end performance leadership at the same sub-$1000 price-points that we’ve had before. NVIDIA on the other hand considers Moore’s Law dead, and says that it’s no longer possible to economically build large high-end GPUs. AMD therefore identified all the components that can do with a slightly older foundry node—such as the L3 cache, memory controllers, and memory PHY, and moved them from the GPU, onto six little dies called MCDs (memory cache dies), which are built on the slightly older 6 nm process. The remaining GPU with all its compute-intensive hardware, would be called the GCD (graphics compute die). The GCD and MCDs would be connected by an extreme bandwidth Infinity Fabric Fanout interconnect, which enables 5.4 TB/s of bandwidth between the GCD and MCDs. Each MCD has a 16 MB segment of the GPU’s total 96 MB Infinity Cache, which is a bit smaller than the 128 MB of the previous generation, but made up for by the 87% higher GDDR6 memory bandwidth from the GPU’s 384-bit memory bus, handling 20 Gbps-rated memory, for 960 GB/s of bandwidth. The RDNA3 graphics architecture which we’re reviewing today, introduces dual issue-rate compute units, with a high degree of optimization in the way idle SIMD resources are utilized, support for newer math formats, and a new AI accelerator that retasks the SIMDs for matrix math functions. Together, these optimizations produce a 17% IPC uplift over the previous-generation RDNA2 CU. There are 96 CUs physically present in the silicon, which work out to 6,144 stream processors. The architecture also sees an increase in engine clocks, and a decoupling of the shader clock speeds to those of the GPU’s Front End, which operates at a 10-15% higher frequency. The most striking aspect of the RDNA3 architecture is that the typical board power of these GPUs is well contained, with the RX 7900 XTX rated at just 350 W, and the RX 7900 XT at 315 W—both of which can be fed by just two 8-pin PCIe power connectors, and cooled by solutions much smaller than those you find on the competing NVIDIA GeForce RTX 4080 or RTX 4090 “Ada.” The Radeon RX 7900 XTX we’re reviewing here, maxes out the “Navi 31” silicon, featuring all 96 compute units, or all 6,144 stream processors, 96 second generation Ray Accelerators, 384 TMUs, a whopping 192 ROPs, and the GPU’s whole 384-bit memory interface, holding 24 GB of 20 Gbps-rated GDDR6 memory. All this for “just” $1,000, or the same price the previous-generation RX 6900 XT debuted at. This is where AMD’s choices with the chiplet architecture begins to make sense, as both of NVIDIA’s competing GPUs are priced much higher. We also have a second Navi 31 review for you today: the Radeon RX 7900 XT.

Radeon RX 7900 XTX Market Segment Analysis

	Price	Cores	ROPs	Core Clock	Boost Clock	Memory Clock	GPU	Transistors	Memory
RTX 3070	$500	5888	96	1500 MHz	1725 MHz	1750 MHz	GA104	17400M	8 GB, GDDR6, 256-bit
RTX 3070 Ti	$600	6144	96	1575 MHz	1770 MHz	1188 MHz	GA104	17400M	8 GB, GDDR6X, 256-bit
RX 6800	$510	3840	96	1815 MHz	2105 MHz	2000 MHz	Navi 21	26800M	16 GB, GDDR6, 256-bit
RX 6800 XT	$650	4608	128	2015 MHz	2250 MHz	2000 MHz	Navi 21	26800M	16 GB, GDDR6, 256-bit
RTX 3080	$750	8704	96	1440 MHz	1710 MHz	1188 MHz	GA102	28000M	10 GB, GDDR6X, 320-bit
RTX 3080 Ti	$950	10240	112	1365 MHz	1665 MHz	1188 MHz	GA102	28000M	12 GB, GDDR6X, 384-bit
RX 6900 XT	$700	5120	128	2015 MHz	2250 MHz	2000 MHz	Navi 21	26800M	16 GB, GDDR6, 256-bit
RX 6950 XT	$800	5120	128	2100 MHz	2310 MHz	2250 MHz	Navi 21	26800M	16 GB, GDDR6, 256-bit
RTX 3090	$950	10496	112	1395 MHz	1695 MHz	1219 MHz	GA102	28000M	24 GB, GDDR6X, 384-bit
RX 7900 XT	$900	5376	192	2000 MHz	2400 MHz	2500 MHz	Navi 31	57700M	20 GB, GDDR6, 320-bit
RTX 3090 Ti	$1400	10752	112	1560 MHz	1950 MHz	1313 MHz	GA102	28000M	24 GB, GDDR6X, 384-bit
RTX 4080	$1200	9728	112	2205 MHz	2505 MHz	1400 MHz	AD103	45900M	16 GB, GDDR6X, 256-bit
RX 7900 XTX	$1000	6144	192	2300 MHz	2500 MHz	2500 MHz	Navi 31	57700M	24 GB, GDDR6, 384-bit
RTX 4090	$2400	16384	176	2235 MHz	2520 MHz	1313 MHz	AD102	76300M	24 GB, GDDR6X, 384-bit