XFX's aftermarket design of the vega 56 shows a cutdown of the pcb to save cost but not really space as the cooler extends the length of a full size pcb and has a nicely designed backplate that also extends the full length to provide much needed support for the cooler.
The cutdown of the pcb should be the only difference, however we also see a redesign of the power delivery system resulting in less chokes and vrms that are also designed to run at a slightly lower temperature(105 vs 115) for maximum efficiency.
Coupled with this power delivery changes is a bios designed to pull 35 watts less than the reference design while retaining similar voltage tables, often resulting in a gpu chip that sits at lower than max speeds due to hitting it's power wall fast.
Through bios or powerplay mods you can remove this limit however you start to reach the crutch of this card, the redesigned power delivery, which is not intended to pull anywhere near 300 watts and results in a vega chip which will never reach it's full potential due to heat issues causing throttling unrelated to the vega chip itself.
Mine also has Hynix HBM which is notably more power hungry to reach higher clocks than the samsung alternative.
All in all this is a great graphics card for someone who wants to game at 1440p with freesync and not worry about overheating, however in the enthusiast community this is by far the worst vega gpu you can buy as it is severely limited by it's redesign.
Should a waterblock emerge for this shorter pcb we might see that change as the itx watercooling community would devour this card.
With some non conventional changes I was able to reach a stable 1650 core clock with HBM at 950 with SOC at 1200 resulting in about 45fps at 4k with all settings maxed in FFXV no gameworks and hbcc(though it might be unnecessary).
Chipset: AMD Vega 56, memory: 8GB HBM2, XFX double dissipation cooling, Radeon VR ready premium, FreeSync 2 technology