New build + recycled bits; No clue whats wrong

[Mhorn2000]

Hey there, I've given it my best shot and now I'm turning to here for my first time for help.
Its a new build with some recycled materials being the RAM, harddrive (with a clean install), 800Watt PSU, and video card.


Current status of computer: turns on half a second, then turns off a few times. It has not powered on since.


Important note: It worked last night perfectly, it ran a high end game just fine. It booted up this morning, but when I tried to fix an audio jack on the front of the case it stopped working (aka, I turned it off, opened the front panel and it never powered on the same after). The parts DO work together when everything is working.


So my main concerns are that the PSU has stopped working or the power button on the front of the case has stopped working, OR the motherboard is toast(?)


What I've Done:
1. checked ALL power supply attachments. **The main power supply to the motherboard is missing what looks like a grounding pin** Looking at the plug I stick into the motherboard they all have copper bits except for that one slot.
2. I've changed power cords on the back.
3. I followed the stickied troubleshooting guide to the point where they have a multimeter. Everything is in order.


Quick edit: So if I flipped the switch on the power supply off for a few seconds, and then turn it back on and then power the front. It'll again turn on for a few brief seconds. Don't know if that means anything.

Hey there, back again. I thought I had solved the problem (aka it started working and recognizing harddrive at same time)

Above is a thread I posted before. I was however wrong on my suspicions.
1. PSU has been multimetered on every ending, and is fine.
2. Motherboard/comp boots up to motherboard interface without harddrive, front panel USBs or dvd drive connected EVERY TIME
3. When hard drive or front panel USBs are connected and powered. It boots briefly and then shuts off.
4. Motherboard detects CPU and RAM just fine.
5. Graphics card has been removed for less complications til later.
6. computer boots with harddrive powered but not connected to motherboard.
7. computer boots with harddrive powered and connected to motherboard but doesn't detect it.
8. computer doesn't boot now with harddrive powered and connected to motherboard (dafuq?)
9. computer boots up with front panel USBs connected to where hard drive was on motherboard.
10. computer boots up with DVD drive connected to motherboard
11. computer boots up with front panel USBs and DVD drive connected to motherboard.
12. NEW: computer boots with harddrive connected to motherboard but no power connected.
So I've gone through this step by step.
Motherboard+hard drive + PSU = no power or no detection.

edits: Hypothesis; my hard drive has been dying for awhile now. This is its end, but how is it connected to the computer turning off? Could it be that when its half alive (zombie?) that the computer shuts off when it detects something wrong there? the data connection is irrelevant from testing. Either cable or plug on all combinations of ends.

NOTE: the hard drive is making a sound.. though in a pattern one long, two short. whatever they are sounds. repetitively.

Edit edit:
13. computer does not boot with dvd drive powered and connected.
14. computer does boot with dvd drive connected and no power

So.. back to my title, I have no clue whats wrong

 

[Mhorn2000]

I've continued to work with the computer some more and I'm still getting the same numbered results. I'm guessing it may be again the PSU, and possibly now the hard drive as well.

 

[avenseth12]

Please provide a list of all your components and the maker (cpu, mobo, psu, etc)

 

[Mhorn2000]

PSU: XION 800watt
CPU: Intel I3-2100
Memory: 8gb (2 sticks) DDR3
Hard Drive: Westen Digital 640gb 7200 RPM
CPU fan: Cooler Master Hyper 212 EVO
DVD drive: hibatchi LG
Motherboard: Gigabyte GA-Z77-D3H

Hope this helps, and thanks for taking a look at this.

 

[FinneousPJ]

That PSU is junk.

 

[Mhorn2000]

Kk, I have another part ordered to replace it. Should I worry about the hard drive too?