Computer switches on for half a second, then turns off

I built my PC earlier today, and when it came around to running it, the lights on the side of the case momentarily started up then switched off after about half a second. I didn't hear my fans/they didn't have time to get started. The issue now is, that I can no longer start the computer up even after removing the plugs etc. It just seems to be dead. All the parts I used were new so I'm not sure what would be the problem. I've already tried the methods listed in the POST sticky that people link too. Help is appreciated.

Just to add, these are the parts I'm using
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More about computer switches half turns
  1. take the motherboard out of the case with just the onboard video and one ram dimm see if the mb will turn on. if it wont take the power supply on the 24 pin atx plug jumper the gree nwire to a black wire see if the unit turns on. if it does read the voltages with a volt meter. see if your missing any or try another test power supply. on your mb lok at the bios rev then look at the motherboard cpu guild make sure the mb will post with that cpu and you have the right bios. some motherboards need bios updates to post.
  2. Okay I tried the MemOK button, and a flash of blue light occurred. Now the button does not do anything so I'm not what this means. I don't think the light came from around the button either.

    Edit: It appears that the blue light is the light from the case LED's. I've tried removing a RAM stick and I still get the same issue. I have to switch the power on and off again to get the blue flash to even occur. At least this means I haven't completely killed everything.
  3. check that the mb on top of the standoffs nothing shorting the mb out. unplug the case fans and usb ports. some times you can have a bad fan. check on the edge of the mb that the eight pin power plug is connected. check yur case header wires make sure there on the right pins.
  4. I checked all the above, but still no luck. The memok button still produces the same flash of the case lights and then switches off until I manually switch the power on and off again. The motherboard light is showing up as green though, so I'm perplexed as to what is wrong.
  5. if your mb is an asus with the usb flashback port try updating the bios. also check to see that your cpu is seated and there no bent pins. if yu have another power supply check that your power supply is working and check for any dead shorts. some times i found cases that had bad fans.with the fans connected to the post.
  6. Tried it and still no luck. I have no idea why it's not working still.
  7. check that the cpu is seated and there no bent pins. use one dimm and no gpu to see if the mb will post. check for any red led when you turn on the power supply.
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