Pushpin tips:
1) Chuck it and buy a bolt through xigmatek hdt-1283.
2) Failing that, carefully push
just the white portion of the pushpin till it goes click all the way through the mobo.
3) Do that for all four.
4) Then, while
holdiing the white portion in, support the back of the mobo right by the pin, and push the black portion in till it gives a nice solid click.
That's the only way i was ever able to get my OEM intel heatsink to mount solidly. Trying to just push the black part like the instructions said never worked. I finally said to hell with it and bought a bolt through cooler.
The above order is what i do, too. PSU goes into the case first though. That may only be because i've been working with old (2002ish) cases that give very little room between mobo and PSU, if i put the mobo in first i can just barely, if at all, get the PSU in.
Modern cases seem to have more room.
In the old days (i built 'em as a business from 96 to 99) you had to put the hard drives in first, as they had to go through space occupied by the mobo when it was installed.
Everything, top to bottom front to back, is much easier now. Be happy
EDIT:
Except heatsink mounting. That was lousy in the early days, and was a bit better by the time i quit, and has now gotten worse. Stupid pushpins