As we’ve gained a better understanding of Thunderbolt 3 external GPU for laptops, the unknown rests on the performance of the host computer. Thin and light laptops are often a top choice to pair with an external GPU. This article serves as the ultrabook buying guide for choosing the best laptop for eGPU. Ultrabooks with Thunderbolt 3 port/s are considered eGPU compatible laptops. Laptops with eGPU support means the manufacturers obtained eGFX certification with Intel. I’ve been testing Razer Blade Stealth + Razer Core V2 in Windows/Linux and 2019 13″ MacBook Pro + Gigabyte Gaming Box in macOS. These pairings are some of the highest performing Thunderbolt 3 ultrabook + external graphics card setups. The Razer Blade Stealth and Apple 13″ MacBook Pro share many fundamental components with a handful of other Thunderbolt 3 laptops that we will explore below.
Intel Thunderbolt Technology website has a long list of certified Thunderbolt 3 ultrabooks. Besides confirming Thunderbolt 3 port/s prerequisite for external GPU for laptop use, it lists standard specs such as hours of battery life, Intel Core i7 or i5 CPU, DDR4 RAM, SSD, FHD or 4K display, usb 3.0 ports, weight, dimensions, bezel thickness, etc. The multitude of choices and information can be overwhelming. Yet the specifications we are most interested in regarding external graphics card for laptop application are not readily available. So then what are the most important criteria you should consider when choosing the best laptop for eGPU pairing? Through thousands of implementations and build guides, we’ve distinguished three key features:
Laptops with ULV CPU
In this article, we’re focusing on the newest crop of laptops with Thunderbolt 3 connectivity. They now sport Intel 8th, 9th, and 10th generation quad-core as well as hexa-core ULV processors, doubling and tripling the core count of the previous generations. The top turbo speed is dependent on both the CPU workload and the ultrabook’s cooling system. If nearing the limits of TDP and CPU junction temperature (95˚-105˚ C), the CPU will throttle down performance. Therefore thin and light laptops are more than skin deep and the best ultrabook for eGPU requires a good cooling system to obtain peak performance.
With nearly identical architecture to the previous generation, the 8th generation ULV CPU offers performance improvements by running double the number of cores, often at a more efficient reduced speed to maintain limits and thereby giving greater overall workload. These ultrabooks are the first revision with quad-core processors and should be future-proof for the next few years. 9th gen processors were somewhat of a stopgap and don’t differ much from 8th gen. Intel 10th generation CPUs have two different families with Comet Lake coming with a top 6-core option and Ice Lake with 4-core with on-die Thunderbolt 3 controller. At this time, the i7-10710U configuration was the highest performing, readily available ULV CPU. Considering external graphics card for laptop application though, the integration of Thunderbolt 3 controller on i7-1065G7 makes it the more appealing choice due to less latency.
|Spec||Intel Core i7-1065G7 @ 1.30GHz||Intel Core i7-10710U @ 1.10GHz|
|Base Speed||1.3 GHz||1.1 GHz|
|Turbo Speed||Up to 3.9 GHz||Up to 4.9 GHz|
|# of Physical Cores||4 (2 logical cores per physical)||6 (2 logical cores per physical)|
|First Seen on Chart||Q2 2019||Q4 2019|
|Single Thread Rating||2,559||2,433|
|CPU Mark (Dec-2019)||10,634||13,115|
Laptops & PCIe Lanes
Thunderbolt connection allows at most 4 PCI Express lanes between the host and the device. In an ULV CPU ultrabook, this means allocating 4 out of a maximum 16 PCIe lanes. There are several peripheral components inside a laptop that make use of these high-speed interconnect lanes. For a typical ultrabook the NVMe flash storage drive gets a x4 PCIe connection. The Wireless card and other components may use a few x1 PCIe connections. If there’s a discrete graphics card, it will consume another x4 PCIe connection. Resource allocation conflicts arise when PC manufacturers decide how best to use these 16 lanes. Due to Thunderbolt 3 connectivity being a relatively new standard, Thunderbolt 3 ports are often not top priority.
One performance hindrance is a x2 PCIe 3.0 via Thunderbolt 3 connection. This is applicable for most single TB3-port ultrabooks, the Razer Blade Stealth being the exception. The Dell XPS 13 is perhaps one of the most popular ultrabooks in the past few years. Many wish to use it with an eGPU, but it’s been plagued with only 2 lanes for its sole Thunderbolt 3 port. The good news is things are gradually changing with the emergence of Thunderbolt 3 external graphics solutions. At CES 2018 I had a discussion regarding this with Gary L., a Dell system engineer. He confirmed 2018 and newer XPS 13 would provide 4 PCIe lanes for its dual Thunderbolt 3 ports.
The HWiNFO64 screen capture on the left shows PCIe configuration in the Razer Blade Stealth. The PCI Express Root Port #5 [A1/C1] attaches to a x4 connection that connects to the Thunderbolt 3 [Alpine Ridge] controller. This controller then hosts a single Thunderbolt 3 port. We also see PCI Express Root Port #3 [A1/C1] attaches to the Killer Wireless-n/a/ac 1535 Network Adapter. Last but not least, PCI Express Root Port #9 [A1/C1] attaches to a Samsung NVMe 960 controller. The HWiNFO64 screen capture (on the right) of a Dell XPS 9360 shows its inferior x2 PCIe connection to the Thunderbolt 3 controller.
OPI Mode in Laptops
An infrequently discussed feature is the On Package DMI interconnect Interface (OPI). ULV processors such as the i7-8550U use OPI because, unlike HQ or HK processors, it lacks the Direct Media Interface (DMI 3.0) to facilitate communication between the PCH and CPU. The system designers can choose to either extract the most performance or optimize energy consumption on these ULV processors. OPI 2GT/s is ideal for extended mobile use at low-power tasks, while OPI 4GT/s is excellent for high-performance applications. These two OPI modes operate at a max theoretical throughput of 20Gbps and 40Gbps respectively. When you consider Intel’s claim of 40Gbps bandwidth for Thunderbolt 3 connectivity, it makes total sense OPI 4GT/s is the more appropriate choice for eGPU use.
Unfortunately the OPI settings are not something users can change at their convenience. The settings are baked into the system firmware/BIOS. At the moment PC manufacturers do not disclose the OPI mode in their marketing information. The only way to find out is to run performance tests yourself. If the ultrabook has an NVMe storage controller, read speed should exceed 1,800 MB/s in benchmark software such as ATTO to confirm the laptop is set to OPI 4GT/s.
As seen in the AIDA64 benchmarks above, OPI 4GT/s systems can extract the most out of Thunderbolt 3 eGPU. Keep in mind that Intel caps the throughput in these eGPU enclosures at roughly 22Gbps to preserve bandwidth for DisplayPort transmission over Thunderbolt 3. As external graphics adoption and demand grows, we hope Intel and partners dedicate more resources to optimize Thunderbolt 3 performance in general and external graphics use in specific.
Best Laptops for eGPU
Below is the best eGPU laptop list that details the trinity of performance specs to host external GPUs. Relatively cheap eGPU laptops are Lenovo 700 series and HP Spectre 13 series. More premium ones are Apple 13″ MacBook Pro, Lenovo X1 Carbon, and Razer Blade Stealth. If you have an Intel 8th gen or newer quad-core+ ultrabook not in this list and can confirm x4 PCIe + OPI 4GT/s, please share your findings by posting a build guide in our forum. We’ll keep this list up-to-date with user reports.
Lenovo Yoga 730
$849i5 Starting MSRPPrice on Lenovo
HP Spectre X360
$1,099i7 Starting MSRPPrice on Amazon
$1,199i7 Starting MSRPPrice on Amazon
Lenovo Yoga 920
$1,299i7 Starting MSRPPrice on Amazon
Dell XPS 13 9370
$1,399i7 Starting MSRPPrice on Amazon
Razer Blade Stealth Featured in article
$1,449i7 Starting MSRPPrice on Amazon
Apple MacBook Pro 13
$1,799i5 Starting MSRPPrice on Amazon
Lenovo Thinkpad X1 Carbon
$2,099i5 Starting MSRPPrice on Lenovo
Higher performance laptops?
Intel released 8th-generation 6-core (hexa) and 9th/10th-generation 8-core (octa) Q 45W CPUs. These come packaged in laptops with larger chassis to accommodate more substantial cooling systems, coupled with bulkier power supplies to drive them. A bigger package that packs a bigger punch. It’s definitely worth the performance advantage if you can trade portability for performance.
Older laptop options?
eGPU.io user builds listed as 32Gbps-TB3 are confirmed to offer full Thunderbolt 3 bandwidth performance. At the link below, you can select LCD, CPU and then review the System Brand and Model widget for options to consider. Proceed to review user builds with your targeted system.
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