Do External Graphics Cards Work for Laptops? eGPUs Explained

This comprehensive guide explores the current state of external graphics cards (eGPUs) for laptops in 2025, addressing whether they truly deliver on their promises and if they’re worth the investment for Kiwi users. We’ll examine how eGPUs function, setup requirements, real-world performance benchmarks, compatibility challenges, and practical use cases across New Zealand’s diverse computing landscape. Plus, we’ll cover the latest Thunderbolt 5 technology, discuss performance trade-offs with actual numbers, and help you determine if an eGPU solution fits your needs or if alternatives like HP’s dedicated gaming laptops might better serve your requirements.

The short answer: Yes, external GPUs work with laptops, but with important caveats about performance and cost that every buyer should understand.

The external graphics processing unit (eGPU) is transforming the world of laptop computing across New Zealand. Before these devices arrived, gamers, creative professionals working in Auckland’s film industry, and other high-performance computer users had to turn to desktop systems for intensive computing needs. Now, eGPUs allow laptop users to achieve desktop-class performance for gaming, 4K video rendering, and AI workloads, but at a cost.

These components are quickly gaining popularity as one of the most popular laptop graphics upgrade options and establishing a devoted fan base amongst New Zealand’s tech enthusiasts.

Read our guide to learn how to turn your laptop into a performance powerhouse with a simple eGPU setup. You’ll also learn how these components work with laptops, what tools you need to get started, and what results to expect in the New Zealand market.

How External Graphics Cards Work with Laptops

An eGPU setup transforms your laptop into a desktop-class workstation, but understanding the technology is crucial before investing.

An external GPU (or eGPU) setup consists of an eGPU box, a desktop-grade graphics card, and a laptop with Thunderbolt connectivity. Most eGPU boxes also come with a built-in power supply and device ports, for USB, Ethernet, and additional displays. Once you dock your laptop to an external monitor, you’ll transform it into a desktop replacement that’s capable of running high-end games, professional creative software, and compute-intensive applications.

Key Components Explained:

  • eGPU Enclosure: Houses the graphics card and provides power
  • Desktop Graphics Card: The actual GPU (NVIDIA RTX 40-series, AMD RX 7000-series)
  • Thunderbolt Connection: The data highway between laptop and eGPU
  • External Monitor: Essential for optimal performance (connecting directly to the eGPU)

Thunderbolt Connections: Which Version Do You Need?

When it comes to connecting your laptop to an eGPU enclosure, there are three main Thunderbolt standards. Each comes with its own power delivery and bandwidth capabilities.

Thunderbolt 3 (2015): The most widely compatible option with 40 Gbps bandwidth, 100W power delivery, and support for 4 PCIe 3.0 lanes. This represents only 25% of a desktop PCIe x16 slot’s bandwidth, creating the biggest performance bottleneck.

Thunderbolt 4 (2020): Maintains the same 40 Gbps bandwidth as TB3, but adds better reliability, cross-device compatibility, and enhanced security features. It also supports 100W charging and guarantees 4K display compatibility.

Thunderbolt 5 (2024): The latest-generation connection offering 80 Gbps bandwidth (with Bandwidth Boost mode reaching 120 Gbps), up to 240W power delivery, and native support for multiple 4K or 8K displays. This is the best option for minimising eGPU performance bottlenecks.

Setting Up an External GPU: What You Actually Need

Before you set up your eGPU, here’s your complete shopping list:

Essential Requirements:

  • Thunderbolt 3/4/5 port on your laptop
  • eGPU enclosure (budget $300-900 NZD)
  • Desktop graphics card (budget $450-2200+ NZD)
  • External monitor (for optimal performance)
  • Updated drivers and BIOS

Thunderbolt Port Check: Verify your laptop has a Thunderbolt port (not just USB-C). Look for the lightning bolt symbol next to the port.

eGPU Enclosure Selection: Choose an enclosure that provides sufficient power for your chosen graphics card. A high-end RTX 4080 needs different power requirements than a mid-range RTX 4060.

Graphics Card Compatibility: Purchase a full-size desktop graphics card. The best current options are NVIDIA RTX 40-series or AMD RX 7000-series cards.

Monitor Connection: Connect your display directly to the eGPU’s video outputs, not your laptop’s built-in screen. This avoids major performance penalties.

Software Updates: Update your laptop’s BIOS, Thunderbolt drivers, and operating system before installation.

How to Install an External GPU for Laptop

Follow this step-by-step installation guide:

Step 1: Verify compatibility between your laptop’s Thunderbolt port and chosen eGPU enclosure.

Step 2: Install the graphics card in your eGPU enclosure. Insert the card firmly into the PCIe slot and secure it with the provided screws.

Step 3: Connect the eGPU enclosure to your laptop using the appropriate Thunderbolt cable (included with most enclosures).

Step 4: Connect the power cable to your eGPU enclosure and power it on.

Step 5: Boot your laptop and check Device Manager (Windows) or System Information (Mac) to verify the GPU is detected. Install GPU drivers if not automatically downloaded.

Step 6: Connect your external monitor directly to the eGPU’s video outputs and set it as your primary display.

Step 7: Test performance with your intended applications. Run benchmarks or games to verify everything functions correctly.

Common Challenges & Solutions to eGPU Installation

Laptop Doesn’t Recognise GPU

Most modern Windows 11 laptops automatically detect eGPUs, but if yours doesn’t: Enable the Thunderbolt device in BIOS settings and manually download GPU drivers from NVIDIA or AMD’s websites.

Dealing with Old Driver Conflicts

Clean driver installation prevents conflicts. Use Display Driver Uninstaller (DDU) to remove old GPU drivers before installing new ones for your eGPU.

GPU Fails to Power On

Power supply mismatch is the most common cause. Verify your eGPU enclosure provides sufficient wattage for your graphics card. High-end cards like RTX 4080/4090 need 650W+ enclosures.

Poor Performance Issues

Performance issues usually stem from using your laptop’s internal display. For best results, always connect an external monitor directly to your eGPU and set it as the primary display.

Performance Reality Check with Real Numbers

eGPUs deliver impressive performance gains, but with measurable limitations compared to desktop setups.

Gaming Performance:

  • Desktop RTX 4070: ~100% performance baseline
  • eGPU RTX 4070 (external monitor): ~85-90% of desktop performance
  • eGPU RTX 4070 (laptop screen): ~70-80% of desktop performance

The performance gap comes from Thunderbolt bandwidth limitations. Even Thunderbolt 5’s 120 Gbps can’t match a desktop PCIe x16 slot’s 256 Gbps bandwidth.

Content Creation Performance:

Video editing, 3D rendering, and AI workloads see smaller performance penalties (typically 5-15%) because these tasks aren’t as bandwidth-sensitive as real-time gaming.

Specific Use Case Performance:

  • 4K video editing: 90-95% of desktop performance
  • 3D rendering: 85-95% of desktop performance
  • Gaming at 1440p: 80-90% of desktop performance
  • Gaming at 4K: 85-92% of desktop performance

Even the top-of-the-line Thunderbolt 5 eGPU, with speeds reaching 120 Gbps, won’t match the speed of a desktop’s PCIe x16 slot. As a result, you can expect some performance loss in an eGPU compared to a desktop. This translates into a 10-20% performance drop for gaming—and this may be even greater if you’re using your laptop’s built-in display.

When it comes to video editing, 3D rendering, and high-intensity AI workloads, you’ll be able to achieve PC-like performance. Bandwidth bottlenecks shrink to nearly zero here, since these aren’t real-time tasks.

HP’s eGPU Philosophy

Rather than competing in the crowded eGPU enclosure market, HP focuses on creating laptops that work flawlessly with existing eGPU solutions whilst offering superior built-in graphics performance in their gaming laptop lineup. This approach ensures New Zealand customers get reliable compatibility and performance from day one.

eGPU Performance with Different Monitor Setups

New Zealand users should particularly consider their display setup when planning an eGPU installation. The performance difference between using your laptop’s internal display versus an external monitor can be substantial:

Internal Laptop Display Performance:

When using your laptop’s built-in screen, the GPU must send rendered frames back through the Thunderbolt connection to display on the laptop screen. This creates additional bandwidth usage and can reduce gaming performance by 15-25%.

External Monitor Performance:

Connecting directly to the eGPU’s display outputs eliminates this bottleneck, providing near-desktop performance levels. This is particularly important for New Zealand’s growing esports community and content creators.

Should You Buy an eGPU in 2025?

eGPUs make sense for specific users, but aren’t the right solution for everyone in New Zealand’s diverse computing landscape.

You SHOULD Consider an eGPU if:

  • You have a premium laptop with Thunderbolt 3/4/5
  • You need occasional high-performance graphics for work or gaming
  • You want to extend your current laptop’s lifespan
  • You have a dedicated workspace with external monitors
  • You work in New Zealand’s film, animation, or creative industries

You Should AVOID eGPUs if:

  • You’re on a tight budget (total cost often exceeds $1200 NZD)
  • You need maximum portability
  • You game primarily on your laptop’s built-in screen
  • A dedicated gaming laptop would cost less than your eGPU setup

Cost Considerations for New Zealand Users

When budgeting for an eGPU setup in New Zealand, consider these realistic cost ranges:

  • Entry-level eGPU setup: $800-1200 NZD (budget enclosure + mid-range GPU)
  • Mid-range eGPU setup: $1200-1800 NZD (quality enclosure + high-performance GPU)
  • High-end eGPU setup: $1800-3000+ NZD (premium enclosure + flagship GPU)

Factor in potential shipping costs and GST for imported components, as local availability may be limited for some eGPU enclosures.

Future of eGPU Technology

The eGPU market continues evolving, with Thunderbolt 5 promising reduced performance bottlenecks and improved user experiences. For New Zealand users considering an eGPU investment, waiting for wider Thunderbolt 5 adoption may provide better long-term value.

However, current Thunderbolt 4 solutions still offer substantial performance improvements for compatible business laptops and premium personal computing systems.

Conclusion

eGPUs represent a compelling solution for specific use cases, particularly for New Zealand’s creative professionals and users with existing premium laptops. However, they’re not a universal solution, and many users will find better value in dedicated gaming systems or high-performance HP laptops that include powerful graphics cards from the start.

Alternative consideration: High-performance gaming laptops like HP’s OMEN series may provide better value and performance than an eGPU setup for many New Zealand users, especially considering local support and warranty coverage.

The bottom line: eGPUs are powerful tools for specific use cases, but carefully calculate total costs and performance expectations before investing. Consider your workspace setup, performance needs, and budget constraints to make the best decision for your computing requirements in New Zealand.

For more guidance on choosing the right computing solution, explore HP’s comprehensive range of laptops, desktops, and accessories designed to meet New Zealand’s diverse computing needs.