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macrumors newbie
Original poster
Oct 8, 2018
I need help buying a Thunderbolt 3 eGPU. I own the MacBook Pro 13" 2018 (2.3GHz i5; 16GB RAM; 256GB SSD). Unfortunately, I don't know much about bottle necks.
Do you have any tips on which GPU and eGPU cases I should buy? The case must have an internal PSU, be upgradeable and work on MacOS and Windows(BootCamp).
Primarily I want to use it for gaming. I don't want a desktop computer ;)


macrumors 6502a
Jan 19, 2007
London, Taipei
Im busy migrating my PC to run exclusively from a eGPU so I can help you with this.

So I've gone for this one, the HP Omen Accelerator half the price of the Razer Core X and with all the ports and an internal SATA connector for a hard drive:

In terms of bottlenecking, this is the deal:
GPU's are capable if utilising PCI Express x16, but all eGPU's are restricted to x4 speed.

In the real world though what that mostly means is that texture load into the GPU's memory buffer is going to be a little slower that it would be compared to if it was connected to a motherboard.

Performance difference really depends, I'm testing mine at the moment and I've had some benchmarks actually run faster (mainly because my MBP has the Core i9, wheras my PC has a 7th Gen Core i7). And some benchmark scores which come out much less on the eGPU.

But real world performance in terms of gaming etc, mostly I'm just seeing I'm losing maybe around 5 - 10 sometimes 20fps from the eGPU but to be fair I have a TitanXP so my frames rates are still well above 30fps anyway.
In terms of video rendering, I dont think you'll see much performance difference.

The only issues I've seen with the HP Omen is that although it does work, HP have concentrated their support exclusively to HP laptops - so really only buy that if you know what you're doing and know how to troubleshoot on your own.


macrumors 6502a
Jan 19, 2007
London, Taipei
Oh, and before I forget, if you need it to work on MacOS and Windows best bet is an AMD GPU.
You can get NVIDIA cards to work, but sometimes you have to deal with manually installing 3rd party drivers. I've personally given up at the moment until we see some drivers working with Mojave.

I only use it in Windows anyway so not a problem for me.


macrumors 6502
Jul 19, 2018
  1. Rule of thumb is that you will lose 10-35% performance from eGPU. More like 25-35%, usually.

  2. Razer Core X is recommended for peak performance, because it doesn't include any other ports or connectors apart from the GPU. It's noob-proof. So the full 4 lanes is dedicated to it (plus the overhead).

    Items like the Omen, or Core, or whatever... they usually ship with drive bays, extra LAN and USB ports, etc. The manufacturers say "wow look how handy this is" but in reality your GPU during gaming is utilising 100% of the 4-lane PCIe bandwidth. Using gigabit network, or 0.5Gbit SATA drives (especially if you run your game on it!) will mean the TB3 connector to laptop is bandwidth starved, and you will see graphics stuttering while command queueing is happening. Long story short, for peak performance, DON'T use anything else on enclosure apart from the GPU slot.

  3. macOS currently only officially supports select AMD cards, as mentioned above. It's laughable as the now last-get 1xxx series Nvidia dominates AMD. Also, bootcamp support is flaky, last I checked, on either AMD/NVIDIA.
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