You're welcome.
By DC-DC converter, do you mean something like the one mentioned in this thread ?
I used an HDPLEX 250W board as I already have two of them ! Reliable, well-known solution, with an already made wire harness 
This way, you can power any GPU up to a R9 Nano, depending on the AC adapter you are using.
However, there is a good news.
As you plan to use a GTX 1050 only, it is possible to get rid of the HDPLEX board and rely on a single 12V brick to power the whole system.
To do so, you need :
- a motherboard that has a wide input DC connector (12V-24V), such as the Gigabyte GA-H110TN. Problem is its DC connector is rated for 10A only, so your only CPU choice is a 35W Intel T CPU.
- a 35W Intel T CPU
- a GTX 1050
- a 10A 12V AC adapter with a 5.5mm DC jack, such as Mini-Box's
- a 4x to 16x powered riser, such a Vary Tech does (website down right now)
To power the riser, you will need a 4-Pin Mini-Fit JR Molex connector to 4-Pin Molex, the motherboard 4-Pin power connector being used as a 12V output.
This is what I plan to do for my next build
Amec Thermasol Flat Coolpipes. Really great product, much more SFF friendly than usual copper heatpipes.
