Introduction

ASUS ROG Strix GeForce RTX 4080 OC is the company's top air-cooled, factory overclocked rendition of the GeForce RTX 4080 "Ada" being launched today, and the company's attempt to beat the NVIDIA Founders Edition in the aesthetics game. Premium multi-tone metal surfaces and a cyberpunk-esque ensemble of shapes concealing RGB LED elements, create something that truly elevates your gaming PC build's appearance. This is also the physically-largest custom-design RTX 4080 we have in our wide selection of custom-design graphics card reviews published for you today.

NVIDIA designed the GeForce RTX 4080 "Ada" with many of the same design goals as its generational flagship launched last month, the RTX 4090. With this card, you get to play any of today's games at 4K Ultra HD with maxed out settings, including ray tracing; but at a more acceptable price-point of $1,200 (NVIDIA baseline price), which is 25% less than that of the RTX 4090. Of course partners like ASUS have done a ton of value-addition, and so their premium custom-designs will be priced higher. This ASUS ROG Strix, for example, is priced at $1550, which is just $50 shy of the RTX 4090 baseline.



The RTX 4080 succeeds both the RTX 3080 10 GB and the RTX 3080 12 GB. This was originally meant to be the RTX 4080 16 GB, with a more affordable $900 12 GB variant supposed to launch today, which NVIDIA decided not to launch due to a branding problem. The RTX 4080 16 GB still has a mighty specs-sheet, with 9,728 CUDA cores, 304 4th gen Tensor Cores, 76 3rd gen RT cores, 304 TMUs, and 112 ROPs. While NVIDIA has enlarged the memory size generationally to 16 GB GDDR6X, the memory bus is actually narrower, at 256-bit. The memory ticks at a higher data-rate of 22.4 Gbps (compared to 19 Gbps of the RTX 3080), and the company enlarged the on-die caches on the silicon, which should make up for the slight bandwidth shortfall.

The ASUS ROG Strix RTX 4080 OC features the same "Vented Exoskeleton" cooling solution that made the RTX 4090 ROG Strix stand out as the most premium custom-design, which is among the largest and heavies air-cooling solutions out there. The card offers factory overclocked speeds of 2.62 GHz compared to 2.50 GHz reference, and all of the premium aesthetic and functional features as the RTX 4090 ROG Strix, with a few handy inclusions such as case fan headers and dual-BIOS.

Architecture

The Ada graphics architecture heralds the third generation of the NVIDIA RTX technology, an effort toward increasing the realism in game visuals by leveraging real-time ray tracing, without the enormous amount of compute power required to draw purely ray-traced 3D graphics. This is done by blending conventional raster graphics with ray traced elements such as reflections, lighting, and global illumination, to name a few. The 3rd generation of RTX heralds the new higher IPC "Ada" CUDA core, 3rd generation RT core, 4th generation Tensor core, and the new Optical Flow Processor, a component that plays a key role in generating new frames without involving the GPU's main graphics rendering pipeline.


The GeForce Ada graphics architecture driving the RTX 4080 leverages the TSMC 5 nm EUV foundry process to increase transistor counts. At the heart of the RTX 4080 is the new AD103 silicon, which has a reasonably large transistor count of 45.9 billion, which is still nearly 60% higher than that of the previous-generation flagship GA102. The GPU features a PCI-Express 4.0 x16 host interface, and a 256-bit wide GDDR6X memory bus, which on the RTX 4080 wires out to 16 GB of memory. With NVIDIA cancelling the 12 GB variant, this is the only RTX 4080 there is, for now. The Optical Flow Accelerator (OFA) is an independent top-level component. The chip features two NVENC and one NVDEC units in the GeForce RTX 40-series.

The essential component hierarchy is similar to past generations of NVIDIA GPUs. The AD103 silicon features 7 Graphics Processing Clusters (GPCs), each of these has all the SIMD and graphics rendering machinery, and is a small GPU in its own right. Each GPC shares a raster engine (geometry processing components) and two ROP partitions (each with eight ROP units). The GPC of the AD102 contains six Texture Processing Clusters (TPCs), the main number-crunching machinery. Each of these has two Streaming Multiprocessors (SM), and a Polymorph unit. Each SM contains 128 CUDA cores across four partitions. Half of these CUDA cores are pure-FP32; while the other half is capable of FP32 or INT32. The SM retains concurrent FP32+INT32 math processing capability. The SM also contains a 3rd generation RT core, four 4th generation Tensor cores, some cache memory, and four TMUs. There are 12 SM per GPC, so 1,536 CUDA cores, 48 Tensor cores, and 12 RT cores; per GPC. There are seven such GPCs, which add up to 10,240 CUDA cores, 320 TMUs, 320 Tensor Cores, 80 RT cores. Each GPC contributes 16 ROPs, so there are 112 ROPs on the silicon. NVIDIA carved the RTX 4080 out of the AD103 by disabling four SMs.


The 3rd generation RT core accelerates the most math-intensive aspects of real-time ray tracing, including BVH traversal. Displaced micro-mesh engine is a revolutionary feature introduced with the new 3rd generation RT core. Just as mesh shaders and tessellation have had a profound impact on improving performance with complex raster geometry, allowing game developers to significantly increase geometric complexity; DMMs is a method to reduce the complexity of the bounding-volume hierarchy (BVH) data-structure, which is used to determine where a ray hits geometry. Previously the BVH had to capture even the smallest details to properly determine the intersection point. Ada's ray tracing architecture receives a major performance uplift from Shader Execution Reordering (SER), a software-defined feature that requires awareness from game-engines, to help the GPU reorganize and optimize worker threads associated with ray tracing.


The BVH now needn't have data for every single triangle on an object, but can represent objects with complex geometry as a coarse mesh of base triangles, which greatly simplifies the BVH data structure. A simpler BVH means less memory consumed and helps to greatly reduce ray tracing CPU load, because the CPU only has to generate a smaller structure. With older "Ampere" and "Turing" RT cores, each triangle on an object had to be sampled at high overhead, so the RT core could precisely calculate ray intersection for each triangle. With Ada, the simpler BVH, plus the displacement maps can be sent to the RT core, which is now able to figure out the exact hit point on its own. NVIDIA has seen 11:1 to 28:1 compression in total triangle counts. This reduces BVH compile times by 7.6x to over 15x, in comparison to the older RT core; and reducing its storage footprint by anywhere between 6.5 to 20 times. DMMs could reduce disk- and memory bandwidth utilization, utilization of the PCIe bus, as well as reduce CPU utilization. NVIDIA worked with Simplygon and Adobe to add DMM support for their tool chains.


Opacity Micro Meshes (OMM) is a new feature introduced with Ada to improve rasterization performance, particularly with objects that have alpha (transparency data). Most low-priority objects in a 3D scene, such as leaves on a tree, are essentially rectangles with textures on the leaves where the transparency (alpha) creates the shape of the leaf. RT cores have a hard time intersecting rays with such objects, because they're not really in the shape that they appear (they're really just rectangles with textures that give you the illusion of shape). Previous-generation RT cores had to have multiple interactions with the rendering stage to figure out the shape of a transparent object, because they couldn't test for alpha by themselves.


This has been solved by using OMMs. Just as DMMs simplify geometry by creating meshes of micro-triangles; OMMs create meshes of rectangular textures that align with parts of the texture that aren't alpha, so the RT core has a better understanding of the geometry of the object, and can correctly calculate ray intersections. This has a significant performance impact on shading performance in non-RT applications, too. Practical applications of OMMs aren't just low-priority objects such as vegetation, but also smoke-sprites and localized fog. Traditionally there was a lot of overdraw for such effects, because they layered multiple textures on top of each other, that all had to be fully processed by the shaders. Now only the non-opaque pixels get executed—OMMs provide a 30 percent speedup with graphics buffer fill-rates, and a 10 percent impact on frame-rates.


DLSS 3 introduces a revolutionary new feature that promises a doubling in frame-rate at comparable quality, it's called AI frame-generation. While it has all the features of DLSS 2 and its AI super-resolution (scaling up a lower-resolution frame to native resolution with minimal quality loss); DLSS 3 can generate entire frames simply using AI, without involving the graphics rendering pipeline. Later in the article, we will show you DLSS 3 in action.


Every alternating frame with DLSS 3 is hence AI-generated, without being a replica of the previous rendered frame. This is possible only on the Ada graphics architecture, because of a hardware component called the optical flow accelerator (OFA), which assists in predicting what the next frame could look like, by creating what NVIDIA calls an optical flow-field. OFA ensures that the DLSS 3 algorithm isn't confused by static objects in a rapidly-changing 3D scene (such as a race sim). The process heavily relies on the performance uplift introduced by the FP8 math format of the 4th generation Tensor core. A third key ingredient of DLSS 3 is Reflex. By reducing the rendering queue to zero, Reflex plays a vital role in ensuring that frame-times with DLSS 3 are at an acceptable level, and a render-queue doesn't confuse the upscaler. A combination of OFA and the 4th Gen Tensor core is why the Ada architecture is required to use DLSS 3, and why it won't work on older architectures.

Packaging

The Card

ASUS created an amazing new look for their GeForce 40 Series graphics cards. Both the main cooler shroud and the backplate are made of thick metal. While the color theme on the backplate is black with silvery highlights, the front introduces gradients of blue and red that look mighty good. The colors change subtly as you adjust your viewing angle of the card.


Dimensions of the card are 36.0 x 15.0 cm, and it weighs 2440 g.


Installation requires three slots in your system.


Display connectivity includes three standard DisplayPort 1.4a ports and two HDMI 2.1a (same technology as Ampere).

NVIDIA introduced the concept of dual NVDEC and NVENC Codecs with the Ada architecture. This means there are two independent sets of hardware-accelerators; so you can encode and decode two streams of video in parallel or one stream at double the FPS rate. The new 8th Gen NVENC now accelerates AV1 encoding, besides HEVC. You also get an "optical flow accelerator" unit that is able to calculate intermediate frames for videos, to smooth playback. The same hardware unit is used for frame generation in DLSS 3.


The card uses the new 12+4 pin ATX 12VHPWR connector, which is rated for up to 600 W of power draw. An adapter cable from 3x PCIe 8-pin is included (which is rated for up to 450 W). Of course the 4x 8-pin to 16-pin adapter cables from RTX 4090 will also work with the RTX 4080, but the card won't need that much power.


This BIOS switch lets you toggle from the default performance BIOS to the quiet BIOS which runs a more relaxed fan curve.


Near the back of the card you'll find two fan headers that run the connected fans at the same speed as the GPU fans, including fan stop. This makes it a great option to control the case fans according to graphics card temperature.

Teardown

The ASUS thermal solution is massive, it uses a vapor-chamber base to soak up heat from the GPU quickly, and seven heatpipes are connected to the heatsink. The main heatsink also provides cooling for the VRM and memory chips.


The backplate is made of thick metal and protects the card against damage during installation and handling.

High-resolution PCB Pictures

These pictures are for the convenience of volt modders and people who would like to see all the finer details on the PCB. Feel free to link back to us and use these in your articles, videos or forum posts.


High-resolution versions are also available (front, back).

Circuit Board (PCB) Analysis

GPU voltage is a 18-phase design, managed by a Monolithic Power Systems MP2888 controller.


Infineon TDA21570 DrMOS components are used for GPU voltage; they are rated for 70 A of current each.


Memory voltage is a three-phase design, managed by a uPI uP9529Q controller.


For memory, Vishay SiC639 DrMOS with a 50 A rating are used.


The GDDR6X memory chips are made by Micron and carry the model number D8BZF, which decodes to MT61K512M32KPA-24. They are specified to run at 1500 MHz (24 Gbps effective).


NVIDIA's AD103 graphics processor is the company's second Ada Lovelace GPU. It is built using a 5 nanometer process at TSMC Taiwan, with a transistor count of 45.9 billion and a die size of 379 mm².