For eGPU, Size Matters
I've been considering to build an eGPU box for years, I still haven't seen all the things I need, but it's close. Here are some of my thoughts of my plan:
For eGPU, size matters.
People looking into eGPUs typically use laptops like MacBook Pro, HP Spectra and ASUS ZenBook 3, they need mobility. When the size of eGPU is same or even bigger than a full blown PC with GTX 1080 Ti, it lost at least half if not most of the purpose. For example, Zotac Magnus EN1080K equiped with GTX 1080 (external power supply), measured at 225x203x128 mm (or 8.86"x8"x5"), a DIY mini-ITX computer with internl SFX power supply measured at 200x118x320 mm (7.87"x4.65"x12.6") I've seen online can literally put a GTX 1080 Ti in it. What is the point if the eGPU is even bulkier than that?
Those branded enclosures such as Razer Core or Akitio Node are designed to host any GPU in the market, they are not compact as eGPUs should be. So if I need an eGPU, I would design and build the enclosure by myself from scratch to meet these requirements:
1. Must be able to install GTX 1080 or better.
2. Must have internal power supply.
3. Must have rounded edges, no part sticks out (think about stuff it into the backpack).
4. Thunderbolt port should provide 30W or more power output (depends on the PCIe 3.0 board I can get, not up to me) so the eGPU can be used as my power brick for the laptop.
How compact can the enclosure be while fulfills all of them? Ideally, the enclosure should be shorter than the depth of the companion laptop in any dimension, but I found it's impossible at this point. To make the enclosure as compact as possible, I have to use Zotac GTX 1080 Mini, the smallest GTX 1080 available:
The Flex (Mini-ITX) power supply is the logical option too (80x40x150mm):
I found these inexpensive aluminium extruded profiles online:
building an enclosure is whole lot easier by using these parts and 3mm aluminium sheets.
It is a tough call to have front 80mm fans or not. The Zotac Magnus 1080 Mini has horizontal heat dissipation fins, front fans could be very efficient to cool down the GPU, and they will help the PCIe board runs at a pleasant temporature. But without the 80mm fans I will make the enclosure 35mm shorter. There is still enough room for a pair of 40mm fans or even a 60mm fan, but that can't compare to a pair of high performance 80mm fans.
If building the enclosure with bended aluminium sheets, the width of the enclosure can be reduced from 92mm to 86mm, though it may not worth all the hassles.
Currently there are 2 exclosures as potential candidates to get the PCIe 3.0 board for the parts, Akitio Node and Sonnet Echo Express SE I/SEL. Akitio has PCIe 3.0 x 16 slot while Sonnet Echo Express has 3.0 x 8 slot, accoring to this article, that doesn't really matter in single card configuration. However, both of them can only provide 15W power output to charge the laptop, I have to wait for other future products for this reason.