Just wanted to follow up on this and share my experience:
Yes, mini PCI-e to external PCI-e adapters do work with the MintBox 2. I tried with an NVidia GT 520M and the performance increase when playing Steam games was very noticeable.
there are some drawbacks to this:
- Intel video will be disabled. As far as I can tell there is no way to enable or use Optimus graphics. When a discrete card is present the Intel graphics are disabled.
- Since you cannot use the Intel video card, the HDMI/DisplayPort outputs on the MintBox do not work. You have to use the video/audio capabilities of your external video card.
- You need to supply 12V to the external adapter for the video card. The MintBox will not provide this for you.
- You also need to manually power cycle the card when you reboot the MintBox. For me this meant instead of rebooting I would shut down the MintBox, power cycle the external graphics card, and then power on the MintBox again.
- You will have an awkward cable sticking out of the MintBox for the external adapter. I ordered an adapter with a flat 30cm ribbon cable that routes nicely out of the chassis below the ethernet ports with zero modification to the MintBox. However, the longer the cable the more clock issues you will have with the PCI-e bus.
- Increased power use. Newer NVidia cards don't use much power when they idle (I've read somewhere around 11W, about what the MintBox draws idle) but when they're in use the power consumption increases dramatically. Low-end cards like the GT 520M are supposed to draw around 30W, the same as a MintBox under full load (with IGP enabled). Mid-range cards like the GTX 650 can draw 70W, and high end cards can easily exceed 100W.
However, there are still a few advantages:
+ No memory used for the IGP, and there is no memory penalty for adding an external GPU (e.g. I can still see and use all 16GB of system RAM).
+ Improved performance.
+ GPU is connected via PCI-e 2.0 x1 link (5GT/s)
A PCI-e 1.0 x16 card has a bandwidth of 40GT/s, so this solution only provides 1/8th the bandwidth a PCI-e 1.0 x16 card would receive. Obviously you are not going to get the full performance out of the discrete card. This article
compares the speed increase from putting a video card in an x16 slot versus an x1 slot. Clearly there is the possibility for a large increase in performance from x1 to x16. But I think that the performance gained from the HD4000 to a discrete solution is probably larger, and you're stuck with an x1 link anyway (unless you fund the development of a FACE module with a PEG port).
In conclusion: you can do it, it seems to offer modest performance gains, but in the end it probably isn't worth it. If you want a small system with a powerful video card just build a Mini-ITX system, it will end up being cleaner and more convenient than this solution is.
However, if your interest is in another PCI-e card (e.g. not a graphics card) then you might consider this more viable. Intel video would still work and you would have access to a full size PCI-e 2.0 x1 slot for whatever kind of card you want to install (network, RAID, video capture, etc).