Alright so here's what's happening, yesterday I left my computer idling (the only program running was Firefox) because I started fiddling with my paintball guns, then out of nowhere, my computer turns off and restarts itself. At that point, I was really confused, but not too worried thinking I'd figure it out once my computer reboots. Well the thing is, is that when it tried to reboot itself, everything gets power and seems to be on, but my LED/Temp gauge on the motherboard is blank (nothing shows at all) as well as getting a black screen.
 
So I did a reset again, but this time resetting the CMOS, and again no LED/Temp gauge and black screen, but all the fans are on and whatnot.
 
Freaking out, I turned off my computer and switched off the PSU.  I then proceed to reseat everything on my computer thinking maybe something was loose. After I was done, I turn on my computer and everything is fine, the motherboard's LED/temp gauge is on and showing me temps (no error codes). The computer at this point is working normally until about 10-15mins in, my computer freezes up and stays like that. I look into my case and I see that the LED/Temp Gauge is also frozen.
 
So I restart my computer and again the LED/Temp Gauge doesn't switch on, but all of the other components do however I keep getting the black screen.
 
This keeps happening over and over where the computer will turn on, but no LED/Temp gauge and a black screen, or if it does bootup and into windows, will be fine only a few minutes and then lock up and I have to turn off.
 
This has gotten supremely frustrating, I have no idea what to do. Is it my PSU? or my Mobo? IS THIS REAL LIFE?!
 
EDIT: Scratch built PC (has been running for about a month now no problems), No O/C ever, no recent drivers/updates/software, the hardest my computer has been pushed is playing Skyrim on ultra settings
 

What you are going to want to do; Is remove the board from the case, and set up on a non condictive mat, to isolate the posability of shorts, when you build outside the case, you are going to want to use as few companants as possable,
 
At that point if you don't have the issue, add componants until you do; If you do have the problem, swap out componants until you don't.
 
When you find the componant causing the issue, RMA or replace it.
 
I am fortunate I have multaple systems which allow for easy trouble shooting, if you Do not, you may have to locate a frind local, to borrow or swap componants with.
 
If you can make the problem move from one system to another, you have found your problem.

Alright, I did what you asked and found out that it was my RAM. Guess I shouldn't spend my money on sale items XD.
Thanks a lot for helping me out!

Ugh. So I had three crashes today. One was after an extended time browsing/minor computing for about 2-3 hours. The second and third were when I was playing Skryim. Each time my computer shuts off and attempts to restart itself but gets stuck in a cycle of booting up, getting to the POST then restarting until I get black screened and my LED/Temp sensor is blank.
 
At the moment, I switched out my triple channel ddr3 1333's to dual channel ddr3 1333's. I'm only using 2 slots. I ran memtest on the triple channel and before the test could even start, the program crashed and restarted ... twice.
 
After that, I used 2 sticks of the dual channel and it was running perfectly until today. Is the problem the DIMM on my MOBO? I'm getting sick of this.
 
EDIT - 04/20/2012 - Turns out it was my RAM timings that were way off. They were set at 6-6-6-20, but my RAM needed 9-9-9-24, which is ridiculous since that should have been the first thing I should have looked for. Thank you for all your trouble Kmoore!