Maybe this is common knowledge I was igorant of, but I figured I'd mention it so others can hopefully avoid it.
So my original modchipped Xbox I've had since about 2002 started having all these weird power issues; the power button wouldn't turn the system on and you had to use the eject button, it wouldn't turn it off unless you held it in for 60 seconds or so, disc drive might eject a half inch then the console power off, and weirdest of all if you unplugged it from the wall it would power on as soon as you plugged it in. I immediately thought it was a power supply issue since I had another one with random shut off problems last year and that was the culprit. Switched the boards out and it made no difference.
Got online and apparently this problem is extremely common. There's a 2.5v capacitor mounted in the lower left corner of the board (toward the P1 controller port) that decides to commit suicide and shoot its load all over that section of the motherboard. That in turn drips down to the underside of the board, which has a bunch of tiny traces that all run parallel to each other in that area and the traces get corroded. In the event just cleaning the mess up doesn't fix it you have to solder in a half dozen jumper wires on some extremely, extremely tiny pads on opposite ends of the board.
Somehow over the years I've wound up with about 8 Xboxes total in various states of disrepair down in my basement (long story). I started cracking these open and, no shit, every single one so far that has this capacitor has leaked all over the board. I think I've went through 6 and of them only 1 was a newer model without that cap. The other 5 had already started oozing out all over that section of the motherboard. None of them were enough to damage anything (yet) but unfortunately the same can't be said for my main machine. One filthy machine that came from a thrift had a nice pattern of yellowish-brown dust bunnies around the cap where they had sucked up most of the liquid as it discharged over time.
All that POS does is keep a charge for the internal clock for a few hours after the electric is unhooked to the console. You don't have to do any soldering to remove it, you can grab it with pliers and just yank it straight out. If you've still got an original Xbox, take it from me, it's worth 5 minutes of your time to jerk that thing out before it ruins your machine. This will inevitably happen unless you remove it.
And on a side note.... do I just have extremely bad luck or are Xbox DVD drives just dogshit? I have 8 machines and only 2 have working drives, and even those are on their last legs. I attempted to use a regular PC drive in one modded box but didn't realize until I had already had spent an hour fooling with the case that you won't be able to read original discs, only stuff on -R's or -RW's. Similar to PS1's, replacement drives are a fool's errand being they cost more than entire used machine.