Basically, all that had happened was that the metal frame part had been bent out of shape a little bit, preventing it from lining up with the slot on the back of the PC
Heh, had a similar issue recently. Either my processor or board died. Not sure which. Figuring out which is too involved to bother. Took a meter to the PSU to rule it out. The readings there were basically perfect. I didn't test it with a load on it because, well, the system wouldn't even post (it would power cycle endlessly). So I just said screw it and picked up a new board and processor. Put those in and it runs like a champ.
Getting to the point.... The new board came with a pre-installed I/O back plate. I'm not sure why this is advertised as such a big deal but whatever. Somehow the pre-installed back plate wasn't pre-installed correctly. The metal flange pieces connecting it to the board were kind of bent and not secured fully so it wasn't lined up right. With a bit of work I managed to get it lined up properly and fit in correctly. I would have sent it back but didn't want to deal with the hassle
.
In terms of building vs buying pre-assembled.... I've always gravitated toward the former as well. Pre-assembled desktop/laptops from "big" brands always seem to come with a ton of junk or sub-par hardware. Or they cost a small fortune. They can also be a pain to upgrade down the road for various reasons. I've always thought with electronics, especially computers, you get what you pay for. If it's too good to be true it most likely is too good to be true. The on sale device or low-priced item is most likely on sale or low priced for a reason. There are exceptions to all of this, of course. Typically it's how it plays out though.
Another consideration is "building" most modern computers isn't as involved or complicated as some people think. It shouldn't be intimidating. It does take work/research but at least you know what you're getting.