What's the difference between a DS3H and D3H motherboard?

Solution
To put it simple, you can put an x1 card like a sound card in an x16 slot, but you can't put an x16 card (like a powerful graphics card) into an x1 slot. The older PCI slots seen on the DS3H aren't really used by modern cards at all, now that PCIe is king.

Both boards have an X16 slot, both are capable of running your RX 470.

Both boards have 4 RAM slots.
The D3H has two PCI slots and two PCIe x16 slots, while the DS3H has one PCIe x16 slot and two PCIe x1 slots. The D3H also has a VRM heatsink while DS3H doesn't.

I'd get the D3H.

BTW, the parts in your built list meet my quality expectations. You have my official thumbs up on your build.
 


Some features of the Gigabyte B250M DS3H and the Gigabyte B250M D3H are the same, but the major differences are the following:

DS3H only has VGA, DVI-D and HDMI on-board display outputs | D3H has VGA, DVI-D, HDMI, and DisplayPort
DS3H has Realtek ALC887 Audio Codec Controller | D3H has Realtek ALC892 Audio Codec Controller
DS3H uses Realtek GbE LAN Controller | D3H uses Intel GbE LAN Controller
DS3H has only 1x PCIe x16 slot running at x16 | D3H has 2x PCIe x16 slots running at x16/x4
DS3H does not support multi-GPU (only single card) | D3H supports multi-GPU (only 2-Way CrossFire)
DS3H has 2x PCIe x1 slots | D3H does not have PCIe x1 slots (but only has 2x PCI slots)
DS3H has 1x M.2 socket that can fit up to 2280 size | D3H has 1x M.2 socket that can fit up to 22110 size
DS3H does not have a SATA Experess connector | D3H has 1x SATA Express connector
DS3H only has a total of 2x fan headers (CPU and case fan) | D3H has 4x fan headers (CPU and 3x case fans)
DS3H only has 3x audio jacks at rear panel | D3H has 6x audio jacks at rear panel
DS3H is mATX at slightly smaller size 226mm x 193mm | D3H is mATX at slightly bigger 244mm x 225mm.
 


If you have a adapter card with a PCIe x1 interface, you can safely plug it in the D3H's second PCIe x16 slot. The first PCIe x16 slot, which is used by your GPU, would still run at full x16 speeds.

Both DS3H and D3H have 4x RAM slots.

If both are the same price, the D3H is the better deal.
 
To put it simple, you can put an x1 card like a sound card in an x16 slot, but you can't put an x16 card (like a powerful graphics card) into an x1 slot. The older PCI slots seen on the DS3H aren't really used by modern cards at all, now that PCIe is king.

Both boards have an X16 slot, both are capable of running your RX 470.

Both boards have 4 RAM slots.
 
Solution