The Efficacy of eGPUs in 2020 - A review of the Sonnet eGFX Rx560 Breakaway Puck
Let's start with the definition of Efficacy:
Efficacy - The quality of being successful in producing an intended result.
It all comes down to the users expectations and the individual use case of the eGPU. If you are using it to improve the graphics processing power. Usually on a computer without a discrete GPU. An Ultrabook is a good example. One of those sub-4-pound laptops that last a whole day on one charge. Those little laptops have little graphics processing power due to integrated graphics. So if you want to edit complex graphics or videos on an Ultrabook you will need an eGPU.
I do have one piece of advice for those who are researching a future eGPU purchase. Curb your enthusiasm. Not that I am saying that eGPUs are not worth it, but you will want to read a lot of reviews. I suggest checking out eGPU.io to help you choose the eGPU that is best for you.
The Sonnet eGFX Rx560 Breakaway Puck
This is a tiny eGPU. Most eGPUs are large, usually the size of a mini iTX chassis. The Breakaway is 6 inches by 5 inches, and is 2 inches tall. It would be the perfect eGPU if it wasn't for the external power brick that is heavier than the eGPU itself. The eGPU has 1 Thunderbolt 3 port, 1 power input (for the AC adapter), 3 Display Ports, and 1 HDMI port. The Display Ports, and HDMI ports are 4K display compatible (HDMI port is capable of 4K at 60Hz). This is just an eGPU. It does not provide any dock functionality, no USB ports, no ethernet ports.
My eGFX Breakaway puck is equipped with a AMD Radeon RX560 GPU with 4GB of Video Memory. From here on out when I talk about eGPUs this will be our test sample. It provides up to 65 Watts of power for charging your computer.
The Sonnet eGFX Rx560 Breakaway Puck is the cheapest pre-built eGPU at $299.
The Niche
eGPUs are really targeted at a niche group. Those who want to use an ultrabook for more than just light computing. Ultrabooks are smaller computers that weigh less than 5 pounds. 13 inch models usually weigh less than 3.5 pounds. They have a reasonable amount of processing power, and have a good amount of battery life. This gives the user a solid day's use with reasonable computational power.
I fit into that category. I wanted a laptop that is small and light. and that I could draw on using a digitizer pen. My laptop of choice is the late 2017 13" HP Spectre X360 with an 8th generation Intel Core i5. It's been a great small laptop, but it lacks sufficient graphics power for large projects. This is our test system.
When the next-generation Thunderbolt is released eGPUs will break away from this niche. There will be more bandwidth allowing larger, more powerful eGPUs to be used. This will also lessen the bandwidth and latency problems making them more effective.
Are eGPUs effective
Yes, eGPUs are effective. For the most part they work like a regular GPU that you would install in a desktop PC. They take the video processing load away from the CPU. To test this I ran several tests in 3D Mark's Skydive test (5 tests per scenario). Below are the screenshots of the median result (the middle result of the 5 tests).
Results without eGPU
Results with eGPU
The catch to an eGPU is that the graphics performance changes based on it's use. Feeding video from the eGPU to the laptop's display works, but there is a performance hit. When you connect the eGPU to an external display the performance improves.
Results with eGPU connected to an external display
As for direct compute performance in Adobe Photoshop and Premiere Rush. I do not have numbers that prove a performance increase (I do not track the speed of macro processes). I can say that it is much faster.
The Law of Diminishing Returns
One of the problems with eGPUs is that almost any desktop GPU can be turned into an eGPU. The problem is that Thunderbolt 3 can be a bottleneck. Thunderbolt 3 is a bus interconnect that provides 4 lanes of PCIe 3.0 through a cable. Just the fact that there is a cable involved adds to the bottleneck. According to my research the more powerful the GPU the more performance you are leaving on the table. That is why lower-end GPUs like the AMD Radeon RX560, RX570, Nvidia GTX 1050, GTX1650 work better. It's more of a scenario that you are actually getting most of the performance you pay for with a lower-end GPU. With high-end GPUs you are paying more money for performance that you cannot tap into. Low-end GPUs demand less from the PCIe bus so they will work better with Thunderbolt 3. This means that spending less money on an eGPU means that you are getting more for your money.
Conclusion
Are eGPUs effective? Yes. Do you need an eGPU? It depends on what you want to use it for. For intense gaming sessions I would say "no." For more middle of the road gaming I would say "yes." For some graphics and video work I would say "yes." It comes down to what you need it to do. If you are after a top-end gaming experience you should build a mini-ITX gaming rig. For casual gaming, and even more than casual gaming, with some work on the side eGPUs are great. It even works well for using an Ultrabook as a second workstation. eGPUs are not a new
