eGPU Explained: What is an External GPU?

The Evolution of External Graphics Processing Units

Consider a scenario where a remarkably thin, lightweight, and aesthetically pleasing laptop could deliver gaming performance comparable to a high-end desktop computer. For a considerable period, enhancing a standard laptop with an external graphics card seemed improbable.

This endeavor was largely confined to experienced do-it-yourself enthusiasts willing to dedicate significant time and effort to intricate circuit board work.

The Rise of eGPU Technology

However, recent advancements in connection standards, coupled with the increasing demands of modern PC games, have propelled the concept of an eGPU closer to mainstream accessibility.

Both computer manufacturers and gaming communities are now recognizing the potential for widespread adoption of external GPU solutions.

Understanding eGPUs: What You Need to Know

What exactly constitutes an eGPU, and why is it gaining attention? The following information will provide clarity.

An eGPU essentially allows users to connect a dedicated graphics card externally to their laptop or other compatible devices.

Key Benefits of Utilizing an eGPU

Enhanced Gaming Performance: Experience desktop-level graphics without the bulk of a traditional gaming PC.
Portability: Maintain the convenience of a laptop while enjoying superior graphical capabilities.
Future-Proofing: Upgrade your graphics card independently of your laptop, extending its lifespan.

The emergence of technologies like Thunderbolt 3 has been instrumental in this development, significantly improving bandwidth and reducing latency.

Note: The eGPU market has undergone substantial changes since the initial publication of this article in 2015, particularly with the widespread adoption of Thunderbolt 3.

Current recommendations for the best eGPUs available in 2020 can be found in updated resources.

The Prevalence of Acronyms

An eGPU, which stands for "External Graphics Processing Unit," represents a concept that has been discussed extensively online and within the research and development divisions of graphics card companies for a considerable period. Essentially, it involves connecting a standard laptop to an external graphics card via a single cable.

This connection allows the more demanding graphical processing tasks to be offloaded from the laptop’s integrated GPU to the more capable external unit.

Related: Selecting Your Next Gaming PC: A Comparison of Building, Buying, and Laptops

The underlying principle is that while many gaming laptops can adequately run less intensive games, such as League of Legends or Dota 2, at moderate settings, achieving optimal performance with graphically demanding AAA titles like Tomb Raider or Batman: Arkham Knight at ultra 4K resolution often pushes the laptop’s hardware to its limits.

This can result in overheating and frequent driver crashes.

An external graphics card functions as a supplemental processing unit. It’s designed for use during stationary gaming sessions at home, but can be disconnected when portability is required.

However, the realization of this concept has been historically constrained by the bandwidth limitations of older connection standards, including USB 2.0, Thunderbolt 2, and FireWire.

Challenges and Enabling Technologies

The functionality of an eGPU is dependent on a fast and reliable connection. Older interfaces simply couldn't provide the necessary data transfer speeds to fully utilize the potential of a powerful external graphics card.

This resulted in significant performance bottlenecks, diminishing the benefits of the external hardware.

USB 2.0: Insufficient bandwidth for practical eGPU applications.
Thunderbolt 2: An improvement, but still limited the performance potential.
FireWire: Not designed for the high data throughput required by modern GPUs.

Recent advancements in connection technologies, particularly Thunderbolt 3 and Thunderbolt 4, have overcome these limitations.

These newer standards offer significantly increased bandwidth, enabling eGPUs to deliver performance much closer to that of a desktop graphics card.

Benefits of Utilizing an eGPU

Employing an eGPU offers several advantages for laptop users. It allows for a substantial graphics performance boost without the need to purchase an entirely new laptop.

This is particularly appealing for individuals who require both portability and high-end gaming capabilities.

Enhanced Gaming Performance: Play demanding games at higher resolutions and settings.
Extended Laptop Lifespan: Upgrade graphics capabilities without replacing the entire system.
Cost-Effectiveness: Potentially more affordable than purchasing a high-end gaming laptop.

The ability to connect and disconnect the eGPU provides flexibility, allowing users to switch between portable and high-performance modes as needed.

The Status of External GPUs in 2015

A significant shift is anticipated shortly, driven by the introduction of Thunderbolt 3.0.

The pursuit of a universally compatible connection has long been a goal. Engineers from companies including AMD, Nvidia, and Intel have dedicated years to developing a cable capable of handling the bandwidth required for graphics card communication with a standalone system.

The Challenge of Bandwidth

In traditional desktop graphics configurations, the GPU connects to the motherboard via a "PCIe x16" slot. The latest version (3.0) can transmit over 15.75 gigabytes per second.

Achieving this level of performance in an external setup has been a major hurdle.

Currently, Thunderbolt 3 represents the most promising solution for a truly plug-and-play external GPU experience. This technology, part of the USB-C family, began appearing in laptops from manufacturers like Acer and Lenovo.

Thunderbolt 3: A Step Forward

Demonstrations of Thunderbolt 3-based eGPUs have been showcased at industry events. However, these remain largely controlled demonstrations, not fully exploring the technology’s potential.

While Thunderbolt 3 offers a doubled speed compared to its predecessor (40Gbps versus 20Gbps in TB2), it still falls short of the bandwidth provided by a standard PCIe 3.0 x16 slot (128Gbps). This difference could impact performance in graphically demanding games.

Real-World Performance

Despite the bandwidth limitations, initial tests by enthusiasts indicate that graphics cards like the Nvidia 750Ti can achieve 80-90 percent of their performance when connected via Thunderbolt 3.

Performance levels vary based on the specific game and the processing power of the host laptop.

The development of products such as MSI's Thunderbolt Gaming Dock suggests growing industry confidence in this new technology.

This indicates that the arrival of practical, plug-and-play external GPUs may be imminent.

The Need for External GPUs

Currently, external GPUs, or eGPUs, remain a relatively niche technology. Their adoption is largely limited to experienced gamers who are comfortable disassembling their laptops to access the mPCIe slot.

However, companies like Alienware and MSI are actively working to expand the accessibility of eGPUs. They are introducing standalone eGPU enclosures, often referred to as "game boxes", designed to broaden the potential user base.

These enclosures, however, currently utilize proprietary cabling systems instead of the more universal Thunderbolt 3 connection. This necessitates the purchase of a compatible, and often expensive, gaming laptop – typically costing $1200 to $1400 – from the same manufacturer.

MSI is developing a new chassis compatible with Thunderbolt 3, capable of accommodating most graphics cards excluding the Nvidia Titan X. A fully functional version, capable of delivering smooth performance in demanding games, is still under development.

Widespread adoption of Thunderbolt 3 across all laptop models, including even budget-friendly ultrabooks, is crucial for the viability of eGPUs. Until then, the complexities involved in setting up an eGPU may outweigh the benefits for many users.

Is an external GPU right for you? In its present state, the answer is likely no.

The limited competition between manufacturers like MSI and Alienware keeps the cost of external docks high, potentially reaching hundreds or even thousands of dollars for a complete setup. At this price point, investing in a dedicated gaming desktop often proves to be a more sensible option.

Nevertheless, the evolution from a hobbyist project to a burgeoning industry suggests that prices may decrease in the near future. As the advantages of transforming laptops into powerful gaming rigs become more apparent, the appeal of traditional desktop computers could diminish.

Image Credits: Dell, Intel, MSI, Lab501