[canhascodez]

I went through something similar building my first PC. I had worked a summer job just to be able to afford one, researched all the parts obsessively, and slowly waited for all of the parts to be shipped to rural Alaska. I put the all of the components in the case, flipped the PSU switch, pressed the power button, and -- nothing, not even a BIOS screen. Five red LEDs were lit on the motherboard, indicating a major hardware fault: CPU, motherboard, RAM, or PSU. Well, there was nothing else for it but to start replacing the parts one by one to see what was broken. It would take a day or two to get the Return Merchandise Authorization, and two weeks shipping time in either direction, so every month or so I would get a new part in to try to get this machine to work.

That went on for about five months. I was crazed with frustration, and a growing pile of electronics boxes, tools, and testing devices filled the corner of my room. I had a collection of components which I was sure were working: the system at least appeared to boot to BIOS when lying on the workbench, but when all the parts were hooked up inside the case, we got five red lights again: major hardware fault. Finally, at the limits of my frustration, I turned to my brother for aid: "It works on the bench, but not in the box. I don't know why. You figure it out."

He returned not five minutes later with the widest grin you can imagine. I was incredulous, and this was a better practical joke than he could ever have devised. He showed me that having the case's reset button (correctly) connected to the motherboard caused the error condition. I was so thankful that I almost didn't want to strangle him!

[seotut2]

I've seen situations such as that. Working outside the case, but not in the case is usually points to a short of the motherboard through the case (of course, assuming it is wired correctly).

[canhascodez]

As I recall, it took me a considerable while to determine that the equipment worked outside the case. I think I tried replacing the RAM, CPU, and PSU before doing the mobo, and unless you have an idea that the case itself might be the issue, well, why would you take the rest of the machine apart? And even if you suspected a board short, you might easily be misled into thinking that it was a part of the case touching the mobo inappropriately, and leave the reset/power leads connected: it's a lot easier to punch the case reset button than to use the tiny one built into the board. And of course, figuring out that the system works without the power switch connected is not super useful in itself: that is something of a necessary component.

I'm just still amazed that he figured it out that quickly; I really didn't tell him much about what had happened, and I'd hardly had time to leave the room before he'd solved it. What a jerk :)