the 1070 is not going to fit, too long. instead I'll be using the AMD RX 570 that I have as backup for now. The motherboard inside the case is matx and I'm familiar with ASRock, MSi, Asus, and Gigabyte. I'm just not familiar with AMD chipset levels compared to Intel's and going with a Ryzen 7 CPU. As I said, this isn't going to be overclocked since the case isn't designed for it. so I'm looking to know which amd matx mobo that is good for gaming without overclocking, not looking at top of the line here to save some money, used with Ryzen 7 cpu (looking at 1700x). the gpu at the moment is on the backburner for now.
Chipset is pretty easy, go with B450 for a 1700X. Avoid X470 (and X570) as the only good reason for one is for a lot of PCIe lanes and that's negated in mATX where the PCIe slots are limited by the form factor. B550 boards aren't an option because Zen1 and Zen 1+ (2000 series) are incompatible.
With a B450 you can upgrade all the way to 5000 series (Zen 3) later on with BIOS updates. B350 should be avoided since they are incompatible for upgrades to Zen 3 but they also have uniformly terrible VRM's across all mfr's. That's bad for for an 8 core CPU.
There are several good B450 motherboards...I'd suggest MSI B450m Mortar MAX, Asus TUF B450m-PRO (not a PLUS) and Asrock B450m Steel Legend. These will handle 1700X even overclocked.
I know you said you don't want to but fixed manual overclocking of a 1st gen is highly recommended to get decent performance. The boosting algorithm isn't as well developed in 1st gen so you'll rarely see it boosting even to it's rated 3.8Ghz, and even more rarely to it's XFR clocks. Boosting is only on light, bursty processing loads; heavy loads will see it struggling even to exceed it's base clock (3.4Ghz) with stock cooling.
These CPU's, based on a 12nm process, are capable of much more with better cooling. A fixed clock of 3.8G-3.9G, all core, is very easy to get with a 1700X. 4.0-4.1G is possible on 'X' cpus but that takes some tuning to find a good voltage and really good cooling; it's really only an indicator of the margin that's in the CPU.
As far as memory: you'll need DDR4 memory. I'd suggest trying to get some 3600 so you're set up for a 5000 series upgrade later on even though you won't get that with a 1700X CPU. But go no less than 3000 speed as that's most likely what you'll get. Although, 3200 is certainly do-able with tweaking. Also, get 2 sticks as 4 sticks is really hard to get clocked higher. Ryzen loves high-clocked memory.
EDIT: And BTW; if you've not got your CPU yet I'd suggest a 1600, 2600X or even 3600X (if you can) if this system is just for gaming.