I also have an Iris! I haven’t tented mine and am trying to decide if I want to.
I’ve found it works fine for games, I usually just shove the right side of my keyboard out of the way for more mouse space, and just have a few extra mouse buttons to make up for not having the right side of the keyboard.
Putting everything together is basically just expensive legos.
As others have mentioned, definitely make sure you are using the motherboard stand-off screws, or that it comes with them pre-attached.
For RAM, it can really only go in one way but it’s a little terrifying when it audibly snaps into place.
If you get everything set up and it doesn’t turn on, first thing I always check is that the RAM is seated properly (motherboard may have recommended configuration depending on the number of RAM sticks).
Make sure you plug your monitor into your GPU, not your integrated graphics from the motherboard.
If you get stuck at any point or have questions, feel free to reach out :)
I’ve put together ~4 computers, 3 in small form factor cases and 1 in a normal sized case. Definitely recommend a modular PSU, and also using cable ties (the Velcro ones that are easy to remove) of some kind for cable management.